Aspen Insurance Holdings Limited (AHL-PC) F-1 20 Dec 23 Registration statement (foreign) Financial data

Cover Page

Cover Page	6 Months Ended
	Jun. 30, 2023
Cover [Abstract]
Document Type	F-1
Entity Registrant Name	ASPEN INSURANCE HOLDINGS LIMITED
Entity Emerging Growth Company	false
Amendment Flag	false
Entity Central Index Key	0001267395

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments:
Debt Securities, Available-for-sale	$ 3,788,600	$ 4,881,600
Short-term investments, available for sale	52,000
Short-term investments, trading at fair value	6,300
Catastrophe bonds, trading at fair value (amortized cost — 2022: $5.1 and 2021: $5.3)	2,900	3,400
Privately-held Investments	533,000	307,100
Investments, equity method	6,200	3,900
Other investments, at fair value (2)	221,300	151,300
Investments, Excluding Derivative Assets	6,085,800	6,516,900
Cash and cash equivalents (including cash within consolidated variable interest entities of — $65.7448377 and $75.15054353)	959,200	1,314,100
Reinsurance recoverables:
Unpaid losses recoverable from reinsurers (net of allowance for expected credit losses of 2022: $3.7 — 2021: $3.3)	4,897,700	3,298,100
Ceded unearned premiums	737,300	596,100
Receivables:
Underwriting premiums receivables (net of allowance for expected credit losses of 2022: $25.0 — 2021: $30.2)	1,482,400	1,304,600
Other receivables	179,400	153,000
Funds withheld	102,600	103,700
Deferred acquisition costs	319,000	290,800
Derivatives at fair value	56,200	12,900
Receivables for securities sold	13,500	19,400
Office properties and equipment	81,300	114,500
Right-of-use operating lease assets	72,800	83,400
Income taxes refundable	20,800	6,400
Deferred tax assets	120,100	0
Other assets	7,400	8,300
Intangible assets and goodwill	21,800	21,900
Total assets	15,157,300	13,844,100
Insurance reserves
Losses and loss adjustment expenses	7,710,900	7,611,800
Unearned premiums	2,457,500	2,112,300
Total insurance reserves	10,168,400	9,724,100
Reinsurance premiums	1,980,100	575,700
Payables
Income taxes payable	10,900	4,400
Deferred tax liabilities	900	2,800
Accrued expenses and other payables (4)	201,800	289,300
Payables for securities purchased	6,900	44,600
Operating lease liabilities	95,500	115,200
Liabilities under derivative contracts	34,900	13,300
Short-term debt	299,900	0
Long-term debt	0	299,900
Total liabilities	12,799,300	11,069,300
Commitments and contingent liabilities (see Note 20)	0	0
Ordinary shares:
60,395,839 ordinary shares of par value $0.01 each (December 31, 2021 — 60,395,839 shares)	604	604
Additional paid-in capital	1,514,700	1,514,700
Retained earnings	1,349,000	1,382,500
Accumulated other comprehensive (loss)	(506,300)	(123,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,358,000	2,774,800
Total liabilities and shareholders’ equity	15,157,300	13,844,100
Fixed Income Investments
Investments:
Debt Securities, Available-for-sale	3,788,600	4,881,600
Fixed Income Investments
Investments:
Debt Securities, Trading	1,475,500	1,157,500
Short-term investments
Investments:
Short-term investments, available for sale	52,000	10,100
Short-term investments, trading at fair value	$ 6,300	$ 2,000

CONSOLIDATED BALANCE SHEETS Con

CONSOLIDATED BALANCE SHEETS Consolidated Balance Sheets (Parenthetical) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	Dec. 31, 2020
Fixed income securities, available for sale amortized cost	$ 4,231,200,000	$ 4,131,300,000	$ 4,823,500,000
Available-for-sale, net of allowance for expected credit losses	4,000,000	7,700,000	2,700,000		$ 200,000
Fixed income securities, trading, amortized cost	1,552,700,000	1,576,700,000	1,155,500,000
Short term investments available for sale, amortized cost	169,300,000	52,400,000	10,100,000
Short-term investments, trading, amortized cost	11,000,000	6,300,000	2,000,000
Catastrophe Bonds, Fair Value Disclosure	2,400,000	5,100,000	5,300,000
Privately-held investments, cost, trading at fair value	496,100,000	537,700,000	309,200,000
Cash and cash equivalents, including cash within variable interest entities	11,400,000	65,700,000	75,200,000
Premium Receivable, Allowance for Credit Loss	$ 21,600,000	$ 25,000,000	$ 30,200,000
Ordinary shares, issued	60,395,839	60,395,839	60,395,839
Ordinary shares, par value	$ 0.01	$ 0.01	$ 0.01
Unpaid losses recoverable from reinsurers (net of allowance for expected credit losses of 2022: $3.7 — 2021: $3.3)	$ 3,300,000	$ 3,700,000	$ 3,300,000		3,800,000
Restricted cash	312,100,000	232,100,000	364,900,000	$ 387,300,000	$ 296,000,000
Privately-held Investments	482,400,000	533,000,000	307,100,000
Other investments, at fair value (2)	213,400,000	221,300,000	151,300,000
Accrued expenses | Asset Management Arrangement
Intercompany funds due to affiliates	2,400,000	4,500,000	3,200,000
Accrued expenses | Management Consulting Agreement
Intercompany funds due to affiliates	2,500,000	1,300,000	0
Apollo originating partnership | Fair Value, Recurring [Member]
Privately-held Investments	42,700,000	44,800,000
Other investments, at fair value (2)	12,600,000	12,700,000
Apollo real estate fund | Fair Value, Recurring [Member]
Other investments, at fair value (2)	22,900,000	25,300,000
Fixed maturities
Fixed income securities, available for sale amortized cost	4,400,500,000	4,183,700,000	4,833,600,000
Short-term investments
Fixed income securities, trading, amortized cost	$ 11,000,000	$ 6,300,000	$ 2,000,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND OTHER COMPREHENSIVE INCOME - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues
Net earned premiums	$ 1,287.4	$ 1,327.2	$ 2,688.7	$ 2,410.5	$ 2,527.5
Net investment income (1)	129.4	88.7	188.1	147.5	154.6
Realized and unrealized investment gains	36.1	2.5	5	56.2	98.5
Other income			8.2	14.7	49.8
Total revenues	1,452.9	1,418.4	2,890	2,628.9	2,830.4
Expenses
Losses and loss adjustment expenses	717.1	767.7	1,680	1,693.3	1,840.8
Acquisition costs	192.9	216.5	431.8	414.1	465.7
General, administrative and corporate expenses (2)	232.7	233.4	494.2	418	410.9
Interest expense	42.9	9.1	43.7	14.3	33.9
Change in fair value of derivatives	(19.6)	84.9	80.5	35.9	65.1
Realized and unrealized investment losses (3)	18.1	128.9	182.6	47.4	27.4
Net realized and unrealized foreign exchange (gains)/losses	(13.7)	75.2	15.9	40	(13.8)
Other expenses			20.1	10.8	10.8
Total expenses	1,197.8	1,365.3	2,917	2,593.8	2,868.4
Income (loss) from operations before income taxes	255.1	53.1	(27)	35.1	(38)
Income tax benefit/(expense)	(36.2)	(4.7)	78.1	(5.3)	(18.4)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Net income/(loss) attributable to Aspen Insurance Holdings Limited’s ordinary shareholders	196.7	26.2
Available for sale investments:
Reclassification adjustment for net realized gains/(losses) on investments included in net income/(loss)	6.8	27.8	55.5	(20.4)	(67.1)
Change in net unrealized (losses)/gains on available for sale securities held	5.5	(343.8)	(447.2)	(137.2)	175.6
Net change from current period hedged transactions	(4.3)	(6.4)	15.4	(6.2)	0.3
Change in foreign currency translation adjustment	7.6	(19.7)	(30.9)	21.4	(11.9)
Other comprehensive (loss)/income, before income taxes	15.6	(342.1)	(407.2)	(142.4)	96.9
Income tax benefit/(expense) thereon:
Change in net unrealized gains on available for sale securities held	(1.6)	29.5	23.9	(0.3)	(0.5)
Total income tax benefit/(expense) allocated to other comprehensive (loss)	(1.6)	30.1	23.9	(0.3)	(0.5)
Other comprehensive (loss)/income, net of tax	14	(312)	(383.3)	(142.7)	96.4
Total comprehensive (loss)/income attributable to Aspen Insurance Holdings Limited's ordinary shareholders	210.7	(285.8)	(332.2)	(112.9)	40
Real estate fund | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(1.3)	0	(1.6)
Asset Management Arrangement
Income tax benefit/(expense) thereon:
Related party fees				(5.8)	(5.3)
Asset Management Arrangement | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(5.2)	(0.6)	(4.9)
Management Consulting Agreement
Income tax benefit/(expense) thereon:
Related party fees				$ (5)	$ (5)
Management Consulting Agreement | General, administrative and corporate expenses
Income tax benefit/(expense) thereon:
Related party fees	(2.5)	(2.5)	(5)
Related party investment income | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(1.7)	(0.2)	(3.1)
Apollo, Class A & B Notes | Gain (Loss) on Investments
Income tax benefit/(expense) thereon:
Related party fees	$ (2)	$ (0.8)	$ (0.4)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Preference shares	Ordinary shares	Preference shares	Additional paid-in capital	Retained earnings	Retained earnings Ordinary shares	Retained earnings Preference shares	Cumulative foreign currency translation adjustments:	Unrealized appreciation on available for sale investments:	Gain on derivatives, net of taxes
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 0.6		$ 1,201.7	$ 1,502.4			$ (165.5)	$ 84.5	$ 4.3
Capital contribution	$ 268
Net income/(loss) for the year	(56.4)
Dividends							$ 0	$ (44.5)
Change for the year, net of income taxes									(11.9)	108
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,887.2		0.6		1,469.7	1,397.2			(177.4)	192.5	4.6
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2016-13 [Member]						(4.3)
Net change from current period hedged transactions											0.3
Total accumulated other comprehensive (loss)/income	19.7
Capital contribution	45
Net income/(loss) for the year	29.8
Dividends							0	(44.5)
Change for the year, net of income taxes									21.4	(157.9)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,774.8		0.6	$ 753.5	1,514.7	1,382.5			(156)	34.6	(1.6)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2016-13 [Member]						0
Net change from current period hedged transactions											(6.2)
Total accumulated other comprehensive (loss)/income	(123)
Net income/(loss) for the year	48.4
Dividends		$ (22.2)					(20)	(22.2)
Change for the year, net of income taxes									(19.7)	(286.5)
Capital contribution	0
Net income/(loss) for the year	51.1
Dividends							(40)	(44.6)
Change for the year, net of income taxes									(30.9)	(367.8)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,469		0.6	753.5		1,388.7			(175.7)	(251.9)	(7.4)
Net change from current period hedged transactions											(5.8)
Total accumulated other comprehensive (loss)/income	(435)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,358		0.6	753.5	$ 1,514.7	1,349			(186.9)	(333.2)	13.8
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2016-13 [Member]						0
Net change from current period hedged transactions											15.4
Total accumulated other comprehensive (loss)/income	(506.3)
Net income/(loss) for the year	218.9
Dividends		$ (22.2)					$ (20)	$ (22.2)
Change for the year, net of income taxes									7.6	10.7
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,548.7		$ 0.6	$ 753.5		$ 1,525.7			$ (179.3)	$ (322.5)	9.5
Net change from current period hedged transactions											$ (4.3)
Total accumulated other comprehensive (loss)/income	$ (492.3)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows (used in)/from operating activities:
Net income/(loss)	$ 51.1	$ 29.8	$ (56.4)
Adjustments to reconcile net income/(loss) to net cash flows from operating activities:
Depreciation and amortization	43.3	53.3	45.8
Impairment of lease assets	(6.7)	0.4	12.9
Amortization of right-of-use operating lease assets	10.1	12	11.8
Interest on operating lease liabilities	5.4	5.5	5.5
Realized and unrealized investment gains	(5)	(56.2)	(98.5)
Realized and unrealized investment losses	182.6	47.4	27.4
Deferred tax expense/(benefit)	(104.6)	(3.2)	(1)
Net realized and unrealized investment foreign exchange (gains)/losses	15.9	13	(25.3)
Net change from current period hedged transactions	15.4	(6.2)	0.3
Unrealized (gain)/loss on real estate fund in net investment income	(14.5)	(20.5)	0
Insurance reserves:
Losses and loss adjustment expenses	99.1	483.3	146.9
Unearned premiums	345.2	310.2	68
Reinsurance recoverables:
Unpaid losses	1,599.6	109.5	864.9
Ceded unearned premiums	(141.2)	(143.1)	(9.6)
Other receivables	(26.4)	(19.4)	(17.4)
Deferred acquisition costs	(28.2)	13.2	(13.3)
Reinsurance premiums payable	1,404.4	1.2	129.7
Funds withheld	1.1	(5.7)	(13)
Premiums receivable	(177.8)	(142.9)	79.9
Income tax payable	(1.3)	(7.6)	7.6
Accrued expenses and other payable	(87)	73.5	2.4
Fair value of derivatives and settlement of liabilities under derivatives	(21.7)	13.6	(87.5)
Long-term debt and loan notes issued by variable interest entities	0	0	0.1
Operating lease liabilities	(15.5)	(17.5)	(17.3)
Other assets	0.9	0.1	(6.8)
Net cash (used in)/from operating activities	(55)	524.7	(672.7)
Cash flows (used in)/from investing activities:
(Purchases) of fixed income securities — Available for sale	(1,613.9)	(2,217.3)	(1,632)
(Purchases) of fixed income securities — Trading	(724.6)	(866.4)	(281.9)
Proceeds from sales and maturities of fixed income securities — Available for sale	2,212.5	1,538.1	2,415.8
Proceeds from sales and maturities of fixed income securities — Trading	293.6	548.2	554.4
Net proceeds from catastrophe bonds — Trading	0.5	14.3	9.8
(Purchases) of short-term investments — Available for sale	(55.9)	(17.2)	(216.1)
Proceeds from sale of short-term investments — Available for sale	13.6	99.6	246.1
(Purchases) of short-term investments — Trading	(7)	(26.8)	(58.3)
Proceeds from sale of short-term investments — Trading	2.6	60.8	103.8
(Purchases) of privately-held investments — Trading	(377.9)	(205.1)	(92.8)
Proceeds from sale of privately-held investments — Trading	147.4	182.1	64.9
Net change in (payable)/receivable for securities (purchased)/sold	(31.8)	26.6	1.5
(Purchases) of other investments	(62.5)	(20)	0
Net proceeds from sales of other investments	5.9	0	71.1
Net sales/(purchases) of fixed assets	3	(64.5)	(40.7)
Investment in multiline reinsurer	(1.6)	(2.5)	(0.5)
Net (purchases)/sales of investments, equity method	(0.4)	(0.2)	6.1
Net cash (used in)/from investing activities	(196.5)	(950.3)	1,151.2
Cash flows used in/from financing activities:
Capital contribution	0	45	268
Dividends paid on ordinary shares	40	0	0
Dividends paid on preference shares	(44.6)	(44.5)	(44.5)
Net cash (used in)/from financing activities	(84.6)	0.5	223.5
Effect of exchange rate movements on cash and cash equivalents	(18.8)	(8.1)	14.8
(Decrease)/increase in cash and cash equivalents	(354.9)	(433.2)	716.8
Cash and cash equivalents at beginning of period	1,314.1	1,747.3	1,030.5
Cash and cash equivalents at end of period (1)	959.2	1,314.1	1,747.3
Restricted cash	232.1	364.9	296
Supplemental disclosure of cash flow information:
Net cash paid during the period for income taxes	29.1	15.7	15
Cash paid during the period for interest	$ 14.3	$ 14	$ 14

CONSOLIDATED BALANCE SHEETS_2

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments:
Debt Securities, Available-for-sale	$ 3,908,200	$ 3,788,600	$ 4,881,600
Short-term investments, available for sale	169,300	52,000
Short-term investments, trading at fair value	11,000	6,300
Catastrophe bonds, trading at fair value (amortized cost — 2022: $5.1 and 2021: $5.3)	2,400	2,900	3,400
Privately-held Investments	482,400	533,000	307,100
Investments, equity method	7,000	6,200	3,900
Other investments, at fair value (2)	213,400	221,300	151,300
Investments, Excluding Derivative Assets	6,272,200	6,085,800	6,516,900
Cash and cash equivalents (including cash within consolidated variable interest entities of — $65.7448377 and $75.15054353)	1,061,500	959,200	1,314,100
Reinsurance recoverables:
Unpaid losses recoverable from reinsurers (net of allowance for expected credit losses of 2022: $3.7 — 2021: $3.3)	4,658,000	4,897,700	3,298,100
Ceded unearned premiums	837,300	737,300	596,100
Receivables:
Underwriting premiums receivables (net of allowance for expected credit losses of 2022: $25.0 — 2021: $30.2)	1,676,800	1,482,400	1,304,600
Other receivables	160,300	179,400	153,000
Funds withheld	59,400	102,600	103,700
Deferred acquisition costs	353,100	319,000	290,800
Derivatives at fair value	17,200	56,200	12,900
Receivables for securities sold	16,600	13,500	19,400
Deferred tax assets	110,900	140,900
Other assets	148,100	161,500
Intangible assets and goodwill	21,700	21,800	21,900
Total assets	15,393,100	15,157,300	13,844,100
Insurance reserves
Losses and loss adjustment expenses	7,740,900	7,710,900	7,611,800
Unearned premiums	2,623,500	2,457,500	2,112,300
Total insurance reserves	10,364,400	10,168,400	9,724,100
Reinsurance premiums	1,833,700	1,980,100	575,700
Payables
Deferred tax liabilities	800	11,800
Accrued expenses and other payables (4)	171,400	201,800	289,300
Payables for securities purchased	46,100	6,900	44,600
Operating lease liabilities	91,300	95,500	115,200
Liabilities under derivative contracts	36,800	34,900	13,300
Short-term debt	299,900	299,900	0
Total liabilities	12,844,400	12,799,300	11,069,300
Commitments and contingent liabilities (see Note 20)	0	0	0
Ordinary shares:
60,395,839 ordinary shares of par value $0.01 each (December 31, 2021 — 60,395,839 shares)	604	604	604
Preference shares, value	753,500	753,500
Additional paid-in capital	761,200	761,200
Retained earnings	1,525,700	1,349,000	1,382,500
Accumulated other comprehensive (loss)	(492,300)	(506,300)	(123,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,548,700	2,358,000	2,774,800
Total liabilities and shareholders’ equity	15,393,100	15,157,300	13,844,100
Fixed Income Investments
Investments:
Debt Securities, Available-for-sale	3,908,200	3,788,600	4,881,600
Fixed Income Investments
Investments:
Debt Securities, Trading	$ 1,478,500	1,475,500	1,157,500
Short-term investments
Investments:
Short-term investments, available for sale		52,000	10,100
Short-term investments, trading at fair value		$ 6,300	$ 2,000

CONSOLIDATED BALANCE SHEETS C_2

CONSOLIDATED BALANCE SHEETS Consolidated Balance Sheets (Parenthetical) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	Dec. 31, 2020
Fixed income securities, available for sale amortized cost	$ 4,231,200,000	$ 4,131,300,000	$ 4,823,500,000
Available-for-sale, net of allowance for expected credit losses	4,000,000	7,700,000	2,700,000		$ 200,000
Fixed income securities, trading, amortized cost	1,552,700,000	1,576,700,000	1,155,500,000
Short term investments available for sale, amortized cost	169,300,000	52,400,000	10,100,000
Short-term investments, trading, amortized cost	11,000,000	6,300,000	2,000,000
Catastrophe Bonds, Fair Value Disclosure	2,400,000	5,100,000	5,300,000
Privately-held investments, cost, trading at fair value	496,100,000	537,700,000	309,200,000
Premium Receivable, Allowance for Credit Loss	$ 21,600,000	$ 25,000,000	$ 30,200,000
Ordinary shares, issued	60,395,839	60,395,839	60,395,839
Ordinary shares, par value	$ 0.01	$ 0.01	$ 0.01
Cash and cash equivalents, including cash within variable interest entities	$ 11,400,000	$ 65,700,000	$ 75,200,000
Unpaid losses recoverable from reinsurers (net of allowance for expected credit losses of 2022: $3.7 — 2021: $3.3)	3,300,000	3,700,000	3,300,000		3,800,000
Restricted cash	312,100,000	232,100,000	364,900,000	$ 387,300,000	$ 296,000,000
Privately-held Investments	482,400,000	533,000,000	307,100,000
Other investments, at fair value (2)	213,400,000	221,300,000	151,300,000
Accrued expenses | Asset Management Arrangement
Intercompany funds due to affiliates	2,400,000	4,500,000	3,200,000
Accrued expenses | Management Consulting Agreement
Intercompany funds due to affiliates	2,500,000	1,300,000	0
Apollo originating partnership | Fair Value, Recurring [Member]
Privately-held Investments	42,700,000	44,800,000
Other investments, at fair value (2)	12,600,000	12,700,000
Apollo real estate fund | Fair Value, Recurring [Member]
Other investments, at fair value (2)	22,900,000	25,300,000
Fixed maturities
Fixed income securities, available for sale amortized cost	4,400,500,000	4,183,700,000	4,833,600,000
Short-term investments
Fixed income securities, trading, amortized cost	$ 11,000,000	$ 6,300,000	$ 2,000,000

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS AND OTHER COMPREHENSIVE INCOME - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues
Net earned premiums	$ 1,287.4	$ 1,327.2	$ 2,688.7	$ 2,410.5	$ 2,527.5
Net investment income (1)	129.4	88.7	188.1	147.5	154.6
Realized and unrealized investment gains	36.1	2.5	5	56.2	98.5
Total revenues	1,452.9	1,418.4	2,890	2,628.9	2,830.4
Expenses
Losses and loss adjustment expenses	717.1	767.7	1,680	1,693.3	1,840.8
Acquisition costs	192.9	216.5	431.8	414.1	465.7
General, administrative and corporate expenses (2)	232.7	233.4	494.2	418	410.9
Interest expense	42.9	9.1	43.7	14.3	33.9
Change in fair value of derivatives	(19.6)	84.9	80.5	35.9	65.1
Realized and unrealized investment losses (3)	18.1	128.9	182.6	47.4	27.4
Net realized and unrealized foreign exchange (gains)/losses	(13.7)	75.2	15.9	40	(13.8)
Total expenses	1,197.8	1,365.3	2,917	2,593.8	2,868.4
Income (loss) from operations before income taxes	255.1	53.1	(27)	35.1	(38)
Income tax benefit/(expense)	(36.2)	(4.7)	78.1	(5.3)	(18.4)
Net (loss)	218.9	48.4	51.1	29.8	(56.4)
Net (loss)/income attributable to Aspen Insurance Holdings Limited’s ordinary shareholders	196.7	26.2
Available for sale investments:
Reclassification adjustment for net realized gains/(losses) on investments included in net income/(loss)	6.8	27.8	55.5	(20.4)	(67.1)
Change in net unrealized (losses)/gains on available for sale securities held	5.5	(343.8)	(447.2)	(137.2)	175.6
Net change from current period hedged transactions	(4.3)	(6.4)	15.4	(6.2)	0.3
Change in foreign currency translation adjustment	7.6	(19.7)	(30.9)	21.4	(11.9)
Other comprehensive (loss)/income, before income taxes	15.6	(342.1)	(407.2)	(142.4)	96.9
Income tax benefit/(expense) thereon:
Change in net unrealized gains on available for sale securities held	(1.6)	29.5	23.9	(0.3)	(0.5)
Change in foreign currency translation adjustment	0	0.6
Total income tax benefit/(expense) allocated to other comprehensive (loss)	(1.6)	30.1	23.9	(0.3)	(0.5)
Other comprehensive (loss)/income, net of tax	14	(312)	(383.3)	(142.7)	96.4
Total comprehensive (loss)/income attributable to Aspen Insurance Holdings Limited's ordinary shareholders	210.7	(285.8)	(332.2)	(112.9)	40
Preference shares
Expenses
Dividends on preference shares	22.2	22.2
Real estate fund | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(1.3)	0	(1.6)
Asset Management Arrangement
Income tax benefit/(expense) thereon:
Related party fees				(5.8)	(5.3)
Asset Management Arrangement | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(5.2)	(0.6)	(4.9)
Management Consulting Agreement
Income tax benefit/(expense) thereon:
Related party fees				$ (5)	$ (5)
Management Consulting Agreement | General, administrative and corporate expenses
Income tax benefit/(expense) thereon:
Related party fees	(2.5)	(2.5)	(5)
Related party investment income | Investment Income
Income tax benefit/(expense) thereon:
Related party fees	(1.7)	(0.2)	(3.1)
Apollo, Class A & B Notes | Gain (Loss) on Investments
Income tax benefit/(expense) thereon:
Related party fees	$ (2)	$ (0.8)	$ (0.4)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Preference shares	Ordinary shares	Preference shares	Additional paid-in capital	Retained earnings	Retained earnings Ordinary shares	Retained earnings Preference shares	Cumulative foreign currency translation adjustments:	Unrealized appreciation on available for sale investments:	Gain on derivatives, net of taxes
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 0.6			$ 1,502.4			$ (165.5)	$ 84.5	$ 4.3
Net income/(loss) for the year	$ (56.4)
Dividends							$ 0	$ (44.5)
Change for the year, net of income taxes									(11.9)	108
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,887.2		0.6			1,397.2			(177.4)	192.5	4.6
Net change from current period hedged transactions											0.3
Total accumulated other comprehensive (loss)/income	19.7
Net income/(loss) for the year	29.8
Dividends							0	(44.5)
Change for the year, net of income taxes									21.4	(157.9)
Preferred stock issuance cost	21.5
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,774.8		0.6	$ 753.5	$ 761.2	1,382.5			(156)	34.6	(1.6)
Net change from current period hedged transactions											(6.2)
Total accumulated other comprehensive (loss)/income	(123)
Aggregate liquidation preferences	775
Net income/(loss) for the year	48.4
Dividends		$ (22.2)					(20)	(22.2)
Change for the year, net of income taxes									(19.7)	(286.5)
Net income/(loss) for the year	51.1
Dividends							(40)	(44.6)
Change for the year, net of income taxes									(30.9)	(367.8)
Preferred stock issuance cost	21.5
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,469		0.6	753.5	761.2	1,388.7			(175.7)	(251.9)	(7.4)
Net change from current period hedged transactions											(5.8)
Total accumulated other comprehensive (loss)/income	(435)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,358		0.6	753.5	761.2	1,349			(186.9)	(333.2)	13.8
Net change from current period hedged transactions											15.4
Total accumulated other comprehensive (loss)/income	(506.3)
Aggregate liquidation preferences	775
Net income/(loss) for the year	218.9
Dividends		$ (22.2)					$ (20)	$ (22.2)
Change for the year, net of income taxes									7.6	10.7
Preferred stock issuance cost	21.5
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,548.7		$ 0.6	$ 753.5	$ 761.2	$ 1,525.7			$ (179.3)	$ (322.5)	9.5
Net change from current period hedged transactions											$ (4.3)
Total accumulated other comprehensive (loss)/income	(492.3)
Aggregate liquidation preferences	$ 775

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows (used in)/from operating activities:
Net income/(loss)	$ 218.9	$ 48.4
Adjustments to reconcile net income/(loss) to net cash flows from operating activities:
Depreciation and amortization	9.6	22
Amortization of right-of-use operating lease assets	5.1	5.2
Interest on operating lease liabilities	2.4	2.8
Net (additions)/disposals of right-to-use operating lease assets	(0.1)	0
Net (additions)/disposals of lease liabilities	0.1	0
Lease repayments	(7.7)	0
Realized and unrealized investment gains	(36.1)	(2.5)
Realized and unrealized investment losses	18.1	128.9
Deferred tax expense/(benefit)	7.5	(2.8)
Gains (Losses) On Investment And Foreign Exchange	(2.3)	18.3
Gain (Loss) on Sale of Derivatives	(4.3)	(5.8)
Unrealized (gain)/loss on real estate fund in net investment income	10.5	(13.5)
Losses and loss adjustment expenses	30	(100)
Unearned premiums	166	381.2
Unpaid losses	239.7	(1,708.4)
Increase (Decrease) in Prepaid Reinsurance Premiums	(100)	(220.7)
Increase (Decrease) in Other Receivables	19.1	(15.2)
Increase (Decrease) in Deferred Policy Acquisition Costs	(34.1)	(24.1)
Reinsurance premiums payable	(146.4)	1,844.2
Increase (Decrease) in Funds Held under Reinsurance Agreements	43.2	11.4
Increase (Decrease) in Premiums Receivable	(194.4)	(275.2)
Income tax payable	9.9	(6.6)
Accrued expenses and other payable	(30.6)	(20.8)
Fair Value Of Derivatives And Settlement Of Liabilities Under Derivatives	40.9	45.1
Other assets	(0.4)	(7.1)
Reinsurance recoverables:
Net cash (used in)/from operating activities	264.6	104.8
Cash flows (used in)/from investing activities:
Payments to Acquire Debt Securities, Available-for-Sale	(789.2)	(695.9)
Payments to Acquire Trading Securities Held-for-investment	(254.6)	(370.9)
Proceeds from sales and maturities of fixed income securities — Available for sale	685.8	1,003.5
Proceeds from sales and maturities of fixed income securities — Trading	283.9	134.8
(Purchases) of short-term investments — Available for sale	(215)	(28.7)
Proceeds from sale of short-term investments — Available for sale	101	9.9
(Purchases) of short-term investments — Trading	(15)	0
Proceeds from sale of short-term investments — Trading	10.4	2
(Purchases) of privately-held investments — Trading	(23.1)	(175.6)
Proceeds from sale of privately-held investments — Trading	58	79
Net change in (payable)/receivable for securities (purchased)/sold	36.1	11.4
(Purchases) of other investments	(3)	(46.6)
Payments for (Proceeds from) Investing Activities, Net of Cash	1.8	0
Net sales/(purchases) of fixed assets	(1.2)	(13.9)
Investment in multiline reinsurer	(0.4)	(1.5)
Net (purchases)/sales of investments, equity method	0	(0.4)
Net cash (used in)/from investing activities	(124.5)	(92.9)
Cash flows used in/from financing activities:
Dividends paid on ordinary shares	(20)	(20)
Dividends paid on preference shares	(22.2)	(22.2)
Net cash (used in)/from financing activities	(42.2)	(42.2)
Effect of exchange rate movements on cash and cash equivalents	4.4	(18.9)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	102.3	(49.2)
Cash and cash equivalents at beginning of period	959.2	1,314.1
Cash and cash equivalents at end of period (1)	1,061.5	1,264.9
Restricted cash	$ 312.1	$ 387.3

History and Organization

History and Organization	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
History and Organization	History and Organization History and Organization. Aspen Insurance Holdings Limited (“Aspen Holdings”) was incorporated on May 23, 2002 as a holding company headquartered in Bermuda. We underwrite specialty insurance and reinsurance on a global basis through our Operating Subsidiaries (as defined below) based in Bermuda, the United States and the United Kingdom: Aspen Bermuda Limited (“Aspen Bermuda”), Aspen Specialty Insurance Company (“Aspen Specialty”), Aspen American Insurance Company (“AAIC”), Aspen Insurance UK Limited (“Aspen UK”) and Aspen Underwriting Limited (“AUL”) (as corporate member of our Lloyd’s operations, Syndicate 4711, which are managed by Aspen Managing Agency Limited (“AMAL”) (together, “Aspen Lloyd’s”)), each referred to herein as an “Operating Subsidiary” and collectively referred to as the “Operating Subsidiaries”. We also have branches in Australia, Canada, Singapore and Switzerland. We established Aspen Capital Management, Ltd. (“ACML”) and other related entities (collectively, “ACM”) to leverage our existing underwriting franchise, increase our operational flexibility and provide third-party investors direct access to our capital markets and underwriting expertise. References to the “Company,” the “Group,” “we,” “us” or “our” refer to Aspen Holdings or Aspen Holdings and its consolidated subsidiaries. Since February 2019, the Company has been a wholly-owned subsidiary of Highlands Bermuda Holdco, Ltd. (“Parent”), which holds all of the Company’s ordinary shares. Parent, a Bermuda exempted company, is an affiliate of certain investment funds managed by affiliates of Apollo Global Management, Inc., a leading global investment manager (collectively with its subsidiaries, “Apollo”). The Company’s preference shares and depositary shares are listed on the New York Stock Exchange (“NYSE”) under the following symbols: AHL PRC, AHL PRD and AHL PRE. History and Organization History and Organization. Aspen Insurance Holdings Limited (“Aspen Holdings”) was incorporated on May 23, 2002 as a holding company headquartered in Bermuda. We underwrite specialty insurance and reinsurance on a global basis through our Operating Subsidiaries (as defined below) based in Bermuda, the United States and the United Kingdom: Aspen Bermuda Limited (“Aspen Bermuda”), Aspen Specialty Insurance Company (“Aspen Specialty”), Aspen American Insurance Company (“AAIC”), Aspen Insurance UK Limited (“Aspen UK”) and Aspen Underwriting Limited (“AUL”) (as corporate member of our Lloyd’s operations, Syndicate 4711, which are managed by Aspen Managing Agency Limited (“AMAL”) (together, “Aspen Lloyd’s”)), each referred to herein as an “Operating Subsidiary” and collectively referred to as the “Operating Subsidiaries”. We also have branches in Canada, Singapore and Switzerland. We established Aspen Capital Management, Ltd. (“ACML”) and other related entities (collectively, “ACM”) to leverage our existing underwriting franchise, increase our operational flexibility and provide third-party investors direct access to our capital markets and underwriting expertise. References to the “Company,” the “Group,” “we,” “us” or “our” refer to Aspen Holdings or Aspen Holdings and its consolidated subsidiaries. Since February 2019, the Company has been a wholly-owned subsidiary of Highlands Bermuda Holdco, Ltd. (“Parent”), which holds all of the Company’s ordinary shares. Parent, a Bermuda exempted company, is an affiliate of certain investment funds managed by affiliates of Apollo Global Management, Inc., a leading global investment manager (collectively with its subsidiaries, “Apollo”). The Company’s preference shares and depositary shares are listed on the New York Stock Exchange (“NYSE”) under the following symbols: AHL PRC, AHL PRD and AHL PRE.

Basis of Preparation and Signif

Basis of Preparation and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Preparation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies The consolidated financial statements of Aspen Holdings are prepared in accordance with United States Generally Accepted Accounting Principles (“U.S. GAAP”) and are presented on a consolidated basis including the transactions of all operating subsidiaries in which the Company has a controlling financial interest and variable interest entities (“VIE”) in which the Company is considered to be the primary beneficiary. Transactions between Aspen Holdings and its subsidiaries are eliminated within the consolidated financial statements. The consolidated financial statements have been prepared on a going concern basis. (a) Use of Estimates Assumptions and estimates made by management have a significant effect on the amounts reported within the consolidated financial statements. The most significant of these relate to losses and loss adjustment expenses, reinsurance recoverables, gross written premiums and commissions which have not been reported to the Company such as those relating to proportional treaty reinsurance contracts, unrecognized tax benefits, recoverability of deferred tax assets, the fair value of derivatives and the fair value of other and privately-held investments. All material assumptions and estimates are regularly reviewed and adjustments made as necessary but actual results could be significantly different from those expected when the assumptions or estimates were made. (b) Accounting for Insurance and Reinsurance Operations Premiums Earned. Premiums are recorded as written on the inception date of a policy. Premiums are recognized as revenues proportionately over the coverage period. Premiums earned are recorded in the consolidated statements of operations, net of the cost of purchased reinsurance. Premiums written which are not yet recognized as earned premium are recorded in the consolidated balance sheet as unearned premiums. Written and earned premiums and the related costs include estimates for premiums which have not been finally determined. These relate mainly to contractual provisions for the payment of adjustment or additional premiums, premiums payable under proportional treaties and delegated underwriting authorities, and reinstatement premiums. Adjustment and additional premiums are premiums charged which relate to experience during the policy term. The proportion of adjustable premiums included in the premium estimates varies between business lines with the largest adjustment premiums being in property and casualty reinsurance, marine, aviation and energy insurance and the smallest in property and casualty insurance. Premiums under proportional treaty contracts and delegated underwriting authorities are generally not reported to the Company until after the reinsurance coverage is in force. As a result, an estimate of these “pipeline” premiums is recorded. The Company estimates pipeline premiums based on projections of ultimate premium taking into account reported premiums and expected development patterns. Reinstatement premiums on assumed excess of loss reinsurance contracts are provided based on experience under such contracts. Reinstatement premiums are the premiums charged for the restoration of the reinsurance limit of an excess of loss contract to its full amount after payment by the reinsurer of losses as a result of an occurrence. The original premiums are recognized as revenue in full at the date of loss, with the reinstatement premiums recognized as revenue over the remaining cover term. Reinstatement premiums provide future insurance cover for the remainder of the initial policy term. An allowance for uncollectible premiums is established for possible non-payment of premium receivables, as deemed necessary. Credit Losses on Underwriting Premiums Receivable. Underwriting premium receivable balances are reported net of an allowance for expected credit losses. The allowance, based on ongoing review and monitoring of amounts outstanding, historical loss data, including write-offs and other relevant factors, is charged to net income in the period the receivable is recorded and revised in subsequent periods to reflect changes in the Company’s estimate of expected credit losses. Credit risk is partially mitigated by the Company’s ability to cancel the policy if the policyholder does not pay the premium. Losses and Loss Adjustment Expenses. Losses represent the amount paid or expected to be paid to claimants in respect of events that have occurred on or before the balance sheet date. The costs of investigating, resolving and processing these claims are known as loss adjustment expenses (“LAE”). The consolidated statements of operations records these losses net of reinsurance, meaning that gross losses and loss adjustment expenses incurred are reduced by the amounts recovered or expected to be recovered under reinsurance contracts. Reinsurance. Written premiums, earned premiums, incurred claims, LAE and the acquisition costs all reflect the net effect of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the Company’s acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance arises from contracts under which other insurance companies agree to share certain risks with the Company. Reinsurance accounting is followed when there is significant timing risk, significant underwriting risk and a reasonable possibility of significant loss. Outward reinsurance premiums, which are paid when the Company purchases reinsurance or retrocessional coverage, are accounted for using the same accounting methodology as the Company uses for inwards premiums. Premiums payable under reinsurance contracts that operate on a “losses occurring during” basis are expensed over the period of coverage while those arising from “risks attaching during” policies are expensed over the earnings period of the underlying premiums written from the reinsured business. Adjustment premiums and reinstatement premiums in relation to outward reinsurance are accrued when it is determined that the ultimate losses will trigger a payment and recognized within premiums payable. Reinsurance and retrocession does not isolate the ceding company from its obligations to policyholders. In the event that a reinsurer or retrocessionaire fails to meet its obligations, the ceding company’s obligations remain. Accounting for Retroactive Reinsurance Agreements. Retroactive reinsurance agreements are reinsurance agreements under which a reinsurer agrees to reimburse the Company as a result of past insurable events. For retroactive reinsurance purchased by the Company, the excess of the amounts ultimately collectible under the agreement over the consideration paid is recognized as a deferred gain liability which is amortized into income over the settlement period of the ceded reserves once the paid losses have exceeded the minimum retention. The amount of the deferral is recalculated each period based on actual loss payments and updated estimates of ultimate losses. If the consideration paid exceeds the ultimate losses collectible under the agreement, the net loss on the retroactive reinsurance agreement is recognized within income immediately. Premiums payable for retroactive reinsurance coverage and meeting the conditions of reinsurance accounting are reported as reinsurance recoverables to the extent that those amounts do not exceed recorded liabilities relating to underlying reinsurance contracts. Premiums paid in excess of accounts receivable are charged to income. Reserves. Insurance reserves are established for the total unpaid cost of claims and LAE in respect of events that have occurred by the balance sheet date, including the Company’s estimates of the total cost of claims incurred but not yet reported (“IBNR”). Claim reserves are reduced for estimated amounts of salvage and subrogation recoveries. Estimated amounts recoverable from reinsurers on unpaid losses and LAE are reflected as assets. For reported claims, reserves are established on a case-by-case basis within the parameters of coverage provided in the insurance policy or reinsurance agreement. For IBNR claims, reserves are estimated using a number of established actuarial methods to establish a range of estimates from which a management best estimate is selected. Both case and IBNR reserve estimates consider variables such as past loss experience, changes in legislative conditions, changes in judicial interpretation of legal liability, policy coverages and inflation. As many of the coverages underwritten involve claims that may not be ultimately settled for many years after they are incurred, subjective judgments as to the ultimate exposure to losses are an integral and necessary component of the loss reserving process. The Company regularly reviews its reserves, using a variety of statistical and actuarial techniques to analyze current claims costs, frequency and severity data, and prevailing economic, social and legal factors. Reserves established in prior periods are adjusted as claim experience develops and new information becomes available. Adjustments to previously estimated reserves are reflected in the financial results of the period in which the adjustments are made. The process of estimating required reserves does, by its very nature, involve considerable uncertainty. The level of uncertainty can be influenced by factors such as the existence of coverage with long duration payment patterns and changes in claims handling practices, as well as the factors noted above. Ultimate actual payments for claims and LAE could turn out to be significantly different from the Company’s estimates. Credit Losses on Reinsurance Recoverables. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability with the reinsured business. The Company evaluates the financial condition of its reinsurers and retrocessionaires, and monitors concentration of credit risk to minimize its exposure to significant losses from individual reinsurers. To further reduce credit exposure on reinsurance recoverables, the Company has received collateral, including letters of credit and trust accounts, from certain reinsurers. Following the adoption of ASC 326, an allowance is established for expected credit losses to be recognized over the life of the reinsurance recoverable. The allowance considers the current financial strength of the individual reinsurer and the amount of collateral held. Acquisition Costs. The costs directly related to writing a (re)insurance policy are referred to as acquisition expenses and include commissions, premium taxes and profit commissions. With the exception of profit commissions, these expenses are incurred when a policy is issued, and only the costs directly related to the successful acquisition of new and renewal insurance and reinsurance contracts are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. Profit commissions are estimated and accrued based on the related performance criteria evaluated at the balance sheet date, with subsequent changes to those estimates recognized when they occur. Commissions received related to reinsurance premiums ceded are netted against broker commissions in determining acquisition costs eligible for deferral. On a regular basis a premium deficiency analysis is performed of the deferred acquisition costs in relation to the expected recognition of revenues, including anticipated investment income, and adjustments, if any, are reflected as period costs. Should the analysis indicate that the acquisition costs are unrecoverable, further analyses are performed to determine if a reserve is required to provide for losses which may exceed the related unearned premium. General and Administrative Expenses. These costs represent the expenses incurred in running the business and include, but are not limited to compensation costs for employees, rental costs, IT development and professional and consultancy fees. General and administrative costs directly attributable to the successful acquisition of business are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. When reporting the results for its business segments, the Company includes expenses which are directly attributable to the segment plus an allocation of central administrative costs. Corporate Expenses. Corporate expenses are not allocated to the Company’s business segments as they typically do not fluctuate with the levels of premium written and are related to the Company’s operations which include group executive costs, group finance costs, group legal and actuarial costs and certain strategic and other costs. (c) Accounting for Investments, Cash and Cash Equivalents Fixed Income Securities. The fixed income securities portfolio comprises securities issued by governments and government agencies, corporate bonds, mortgage and other asset-backed securities and bank loans. Investments in fixed income securities are classified as available for sale or trading and are reported at estimated fair value in the consolidated balance sheet. Investment transactions are recorded on the trade date with balances pending settlement reflected in the consolidated balance sheet under receivables for securities sold and other payables for securities purchased, respectively. Fair values are based on quoted market prices and other data provided by third-party pricing services. Short-term Investments. Short-term investments primarily comprise highly liquid debt securities with a maturity greater than three months but less than one year from the date of purchase and are held as part of the investment portfolio of the Company. Short-term investments are classified as either trading or available for sale and reported at estimated fair value. Catastrophe Bonds. Investments in catastrophe bonds are classified as trading and are reported on the consolidated balance sheet at estimated fair value. The fair values are based on independent broker-dealer quotes. Privately-held Investments. The Company’s privately-held investments primarily comprise commercial mortgage loans, middle market loans, asset-backed securities, global corporate securities and equity securities. These investments are classified as trading and are reported on the consolidated balance sheet at estimated fair value. Privately-held investments are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are primarily determined using internally developed discounted cash flow models. Interest income is accrued on the principal amount of the loan based on its contractual interest rate subject to it being probable that we will receive interest on that particular underlying loan. Interest income, amortization of premiums and discounts, and prepayment fees are reported in net investment income on the consolidated statements of income. Other Investments, Equity Method. Other investments represent the Company’s investments that are recorded using the equity method of accounting. Adjustments to the fair value of these investments are made based on the net asset value of the investment. Other Investments. Other investments represent the Company’s investments in real estate funds and other special purpose vehicles. Adjustments to the fair value are made based on the net asset value of the investment. Cash and Cash Equivalents. Cash and cash equivalents are reported at fair value. Cash and cash equivalents comprise cash on hand, deposits held on call with banks and other short-term highly liquid investments due to mature within three months from the date of purchase and which are subject to insignificant risk of change in fair value. Gains and Losses. Realized gains or losses on the sale of investments are determined on the basis of the first in first out cost method and are recorded in revenue or expenses respectively. Unrealized gains and losses represent the difference between the cost, or the cost as adjusted by amortization of any difference between its cost and its redemption value (“amortized cost”), of the security and its fair value at the reporting date and are included within other comprehensive income for securities classified as available for sale and in realized and unrealized investment gains or losses in the consolidated statement of operations for securities classified as trading. Credit Losses on Available for Sale Debt Securities . Following Aspen’s adoption of ASU 2016-13 “Financial Instruments - Credit Losses (Topic 326)” , effective January 1, 2020, current expected credit losses (CECL) are recognized through an allowance account for available for sale debt securities, thereby permitting reversals of previously recognized credit losses through net income in the period they occur. Write-offs (of any previously recognized allowance for credit losses) are recorded when amounts are deemed uncollectible, or Aspen intends to sell (or more likely than not will be required to sell) the debt security before recovery of the amortized cost basis. The amortized cost basis will be written down to the debt securities fair value through earnings. Credit losses are limited to the difference between the debt securities amortized cost basis and fair value (‘fair-value floor’). Any decline in the debt securities fair value below the amortized cost basis that is not a result of a credit loss is recorded through other comprehensive income, net of applicable taxes. Our credit loss models employ a discounted cash flow approach to evaluate whether a credit loss exists at the individual security level and are reviewed at each reporting period. This analysis excludes investments in U.S. Government / Agency bonds and U.S. Government Agency mortgage-backed securities due to being of ‘high credit quality’ based on the absence of risk. Available for sale debt securities that were initially purchased with credit deterioration (PCD), the amortized cost basis shall be considered to be the purchase price, plus any allowance for credit losses. Estimated credit losses shall be discounted at the rate that equates the present value of the purchaser’s estimate of the security’s future cash flows with the purchase price of the asset. Holding gains or losses are recognition through other comprehensive income, net of applicable taxes. No changes in the estimate of credit losses have taken place during the period. Net Investment Income. Investment income includes amounts received and accrued in respect of periodic interest (“coupons”) payable to the Company by the issuer of fixed income securities, equity dividends and interest credited on cash and cash equivalents. It also includes amortization of premium and accretion of discount in respect of fixed income securities. Investment income also includes changes in fair value from investments in real estate funds. Investment management and custody fees are charged against net investment income reported in the consolidated statement of operations. (d) Accounting for Derivative Financial Instruments The Company enters into derivative instruments such as interest rate swaps and forward exchange contracts in order to manage certain market and credit risks. The Company records derivative instruments at fair value on the Company’s consolidated balance sheet as either assets or liabilities, depending on their rights and obligations. The accounting for the gain or loss due to the changes in the fair value of these instruments is dependent on whether the derivative qualifies as a hedge. If the derivative does not qualify as a hedge, the gains or losses are reported in the consolidated statement of operations when they occur. If the derivative qualifies as a hedge, the accounting treatment varies based on the type of risk being hedged. Gains and losses on the effective portion of such contracts are recognized in other comprehensive income. As the contracts settle, the realized gain or loss is reclassified from other comprehensive income into the consolidated statement of operations. The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangements is considered an embedded derivative and accounted for as an option-based derivative. Since the economic characteristics and risks of an embedded derivative feature are not clearly and closely related to the economic characteristics and risks of the host contract, the embedded derivative is bifurcated and accounted for separately at fair value. The Company records subsequent changes in the embedded derivative fair value in the consolidated statement of operations. (e) Accounting for Intangible Assets Intangible assets are held in the consolidated balance sheet at cost less amortization and impairment. Amortization applies on a straight-line basis in respect of assets having a finite estimated useful economic life. Finite intangibles are assessed on an annual basis for impairment, or more frequently where circumstances indicate the carrying value may not be recoverable. For intangible assets considered to have an indefinite life, the Company performs a qualitative assessment annually to determine whether it is more likely than not that an intangible asset is impaired. Goodwill is assessed annually for impairment or more frequently if circumstances indicate an impairment may have occurred. (f) Accounting for Office Properties and Equipment Office properties and equipment are reported at cost less accumulated depreciation. These assets are depreciated on a straight-line basis over the estimated useful lives of the assets. Computer equipment is depreciated between three IT development costs that are directly associated with the development of identifiable and unique software products and that are anticipated to generate economic benefits exceeding costs beyond one year, are recognized within office properties and equipment. Costs include external consultants’ fees, certain qualifying internal staff costs and other costs incurred to develop software programs. Software is depreciated over their estimated useful life, between three and five years, on a straight-line basis and is subject to impairment testing annually. Depreciation commences when the asset becomes operational. Other non-qualifying costs are expensed as incurred. (g) Accounting for Leases In the ordinary course of the business, the Company renews and enters into new leases for office real estate and other assets. At the lease inception date, the Company determines whether a contract contains a lease and recognizes operating lease Right-of-use assets and operating lease liabilities based on the present value of future minimum lease payments. As our leases do not provide an implicit interest rate, we use our incremental borrowing rate based on the information available at the commencement date to determine the present value of future payments. For all office real estate leases, rent incentives, including reduced-rent and rent free periods and contractually agreed rent increases during the lease term, have been included when determining the present value of future cash flows. Right-of-use operating lease assets are reported at cost less accumulated depreciation on the consolidated balance sheet and depreciated over the lease term. The Company does not record office property and equipment leases with an initial term of 12 months or less (short-term) in the Company's consolidated balance sheets. Such short-term leases are expensed through the consolidated statement of operations. Right-of-use operating lease assets are tested for impairments whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. If the carrying value of an asset is impaired, it is reduced to the recoverable amount by an immediate charge to the income statement. The recoverable amount is the higher of an asset’s fair value less costs to sell and value in use. (h) Accounting for Foreign Currencies Translation The reporting currency of the Company is the U.S. Dollar. Effective January 1, 2022, management reassessed its functional currency determination in accordance with ASC 830, Foreign Currency Matters, as a result of significant changes in the Group’s economic facts and circumstances, and concluded that the functional currency of certain of its foreign operations had changed. Consequently, the Company has concluded that the U.S. Dollar is now the functional currency for all its branches and overseas entities. The change in the Company’s functional currency determination has been applied on a prospective basis in accordance with ASC 830. Therefore, any translation gains and losses that were previously recorded in accumulated other comprehensive income through December 31, 2021 remain unchanged through December 31, 2021. From January 1, 2022, any net realized and unrealized gains/(losses) on translation are recognized in the consolidated statements of operations and other comprehensive income (loss). Investments classified as available-for-sale are recorded at fair value, the portion attributable to movements in exchange rates continues to be included within accumulated other comprehensive income. Transactions in currencies other than the functional currency are measured at the exchange rate prevailing at the date of the transaction. Monetary assets and liabilities denominated in non-functional currencies are remeasured at the exchange rate prevailing at the balance sheet date and any resulting foreign exchange gains or losses are reflected in the consolidated statement of operations. Non-monetary assets and liabilities are remeasured to functional currency at historic exchange rates. (i) Accounting for Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. When the Company does not believe that, on the basis of available information, it is more likely than not that deferred tax assets will be fully recovered, it recognizes a valuation allowance against its deferred tax assets to reduce the deferred tax assets to the amount more likely than not to be realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Furthermore, a tax benefit from a tax position may be recognized in the financial statements only if it is more-likely-than-not that the position is sustainable, based solely on its technical merits and consideration of the relevant tax authority’s widely understood administrative practices and precedents. The Company applies a portfolio approach to release the income tax effects in accumulated other comprehensive income. Under this approach, the income tax effects upon the sale of an available-for-sale debt security, settlement of hedged transactions and upon foreign currency translation adjustments for each period, are determined under the intraperiod tax allocation approach. Any tax effects remaining in accumulated other comprehensive income are only released when the entire portfolio is liquidated, sold or extinguished. (j) Accounting for Preference Shares The Company had at the balance sheet date in issue three classes of preference shares. The Company has no obligation to pay interest on these securities but they carry entitlements to dividends payable at the discretion of the Board of Directors. In the event of non-payment of dividends for six consecutive periods, holders of preference shares have director appointment rights. The preference shares are therefore accounted for as equity instruments and included within total shareholders’ equity. (k) Accounting for Long-Term Incentive Plans The Company operates an employee long-term incentive plan, comprised of Performance Units and Exit Units, the terms and conditions of which are described in Note 16. The Company applies a fair-value based measurement method in calculating the compensation costs of Performance Units which are recognized on a straight-line basis over the vesting period. (l) Accounting for Business Combinations The Company accounts for a transaction as a business combination where the assets acquired and liabilities assumed following a transaction constitute a business. An acquired entity must have inputs and processes that make it capable of generating a return or economic benefit to be considered a business. If the assets acquired are not a business, the Company accounts the transaction as an asset acquisition. The Company recognizes and measures at fair value 100 percent of the assets and liabilities of any acquired business. Goodwill is recognized and measured as the difference between the consideration paid or payable less the fair value of assets acquired. The Company accounts for the disposal of subsidiary undertakings when it ceases to control the subsidiary’s assets and liabilities or the group of assets. A gain or loss is recognized and measured as the difference between the fair value of consideration received or receivable and the value of assets, liabilities and equity components de-recognized, related to that subsidiary or group of assets when deconsolidated. Costs that are directly related to a business combination transaction are expensed in the periods in which the costs are incurred and the services are received. (m) Accounting Pronouncements Accounting Pronouncements Adopted In March 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326 )”. This update is as a result of a post implementation review done on the issued ASU No.2016-13 , Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , addressing “troubled debt restructuring by creditors” and “vintage disclosures”. This update will be effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Accounting Pronouncements Not Yet Adopted In March 2022, the FASB issued Accounting Standards Update No. ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging, Portfolio Layer Method ”. This update addresses concerns from entities and practitioners regarding the ‘last-of-layer’ method of accounting incorporated in update No. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” , issued on 28 August, 2017. This method is meant to achieve fair value hedge accounting for interest rate risk hedges of portfolios of ‘prepayable financial assets’. This ASU will be effective for fiscal years beginning after December 15, 2023 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In June 2022, the FASB issued Accounting Standards Update No. ASU 2022-03, “Fair Value Measurement (Topic 820 )”. This update is for entities that have investments in equity securities, measured at fair value, which are subject to a contractual sale restriction. This update will be effective for fiscal years beginning after December 15, 2024 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In September 2022, the FASB issued Accounting Standards Update No. ASU 2022-04, “Liabilities- Supplier Finance Programs (Subtopic 405-50)” . The update has been issued to enhance the transparency of supplier finance progr

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company manages its underwriting operations as two business segments: Aspen Reinsurance and Aspen Insurance. The Company has determined its reportable segments by taking into account the manner in which management makes operating decisions and assesses operating performance. Profit or loss for each of the Company’s business segments is measured by underwriting income or loss. Underwriting profit is the excess of net earned premiums over the sum of losses and loss expenses, acquisition costs and general and administrative expenses. Underwriting income or loss provides a basis for management to evaluate the segment’s underwriting performance. Reinsurance Segment. The reinsurance segment consists of property catastrophe reinsurance, other property reinsurance, casualty reinsurance and specialty reinsurance. Insurance Segment. The insurance segment consists of first party and specialty insurance, casualty and liability insurance and financial and professional lines insurance. Additionally, the insurance segment includes Aspen Underwriting Limited’s participation as a corporate member in Carbon Syndicate 4747 (“Carbon Syndicate”). Non-underwriting Disclosures. The Company provides additional disclosures for corporate and other (non-operating) income and expenses. Corporate and other income and expenses include: corporate expenses, net investment income, net realized and unrealized investment gains or losses, other strategic and other costs, changes in fair value of derivatives or the loan notes issued by variable interest entities, interest expenses, net realized and unrealized foreign exchange gains or losses, asset impairments and income taxes. These income and expense items are not allocated to the Company’s business segments as they are not directly related to the Company’s business segment operations and is consistent with how management measures the performance of its segments. The Company does not allocate its assets by business segment. The Company uses underwriting ratios as measures of performance. The loss ratio is the ratio of losses and loss adjustment expenses to net earned premiums. The acquisition cost ratio is the ratio of acquisition costs to net earned premiums. The general and administrative expense ratio is the ratio of general and administrative expenses to net earned premiums. The combined ratio is the sum of the loss ratio, the acquisition cost ratio and the general and administrative expense ratio. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for the twelve months ended December 31, 2022, 2021 and 2020: Twelve Months Ended December 31, 2022 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,807.0 $ 2,531.7 $ 4,338.7 Net written premiums 1,426.4 1,469.6 2,896.0 Gross earned premiums 1,617.2 2,370.8 3,988.0 Net earned premiums 1,251.8 1,436.9 2,688.7 Underwriting Expenses Losses and loss adjustment expenses 770.3 909.7 1,680.0 Acquisition costs 252.4 179.4 431.8 General and administrative expenses 142.5 244.0 386.5 Underwriting income 86.6 103.8 190.4 Corporate expenses (71.7) Non-operating expenses (1) (36.0) Net investment income 188.1 Realized and unrealized investment gains 5.0 Realized and unrealized investment losses (182.6) Change in fair value of derivatives (80.5) Interest expense (43.7) Net realized and unrealized foreign exchange gains 15.9 Other income 8.2 Other expenses (20.1) (Loss) before income taxes (27.0) Income tax benefit 78.1 Net income $ 51.1 Net reserves for loss and loss adjustment expenses $ 1,360.7 $ 1,452.5 $ 2,813.2 Ratios Loss ratio 61.5 % 63.3 % 62.5 % Acquisition cost ratio 20.2 12.5 16.1 General and administrative expense ratio 11.4 17.0 14.4 Expense ratio 31.6 29.5 30.5 Combined ratio 93.1 % 92.8 % 93.0 % ________________ (1) Non-operating expenses includes $32.7 million in relation to fixed assets written off, $10.0 million of severance, consulting and professional services in relation to non-recurring projects and other costs, offset by $6.7 million of write backs related to leased office space. Twelve Months Ended December 31, 2021 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,597.0 $ 2,341.4 $ 3,938.4 Net written premiums 1,199.0 1,388.7 2,587.7 Gross earned premiums 1,479.2 2,139.1 3,618.3 Net earned premiums 1,118.8 1,291.7 2,410.5 Underwriting Expenses Losses and loss adjustment expenses 705.2 988.1 1,693.3 Acquisition costs 221.6 192.5 414.1 General and administrative expenses 121.3 211.8 333.1 Underwriting income/(loss) 70.7 (100.7) (30.0) Corporate expenses (64.3) Non-operating expenses (1) (20.6) Net investment income 147.5 Realized and unrealized investment gains 56.2 Realized and unrealized investment losses (47.4) Change in fair value of derivatives (35.9) Interest expense (14.3) Net realized and unrealized foreign exchange gains 40.0 Other income 14.7 Other expenses (10.8) Income before income taxes 35.1 Income tax (expense) (5.3) Net income $ 29.8 Net reserves for loss and loss adjustment expenses $ 2,148.4 $ 2,165.3 $ 4,313.7 Ratios Loss ratio 63.0 % 76.5 % 70.2 % Acquisition cost ratio 19.8 14.9 17.2 General and administrative expense ratio 10.8 16.4 13.8 Expense ratio 30.6 31.3 31.0 Combined ratio 93.6 % 107.8 % 101.2 % ________________ (1) Non-operating expenses includes $19.3 million of costs related to consulting and professional services in relation to non-recurring projects and other costs, $0.4 million of impairment charges related to lease assets as a result of exiting certain office space and $0.9 million of amortization of intangible assets and other non-operating expenses. Twelve Months Ended December 31, 2020 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,656.4 $ 2,042.1 $ 3,698.5 Net written premiums 1,297.7 1,280.1 2,577.8 Gross earned premiums 1,612.0 2,026.4 3,638.4 Net earned premiums 1,287.7 1,239.8 2,527.5 Underwriting Expenses Losses and loss adjustment expenses 958.6 882.2 1,840.8 Acquisition costs 246.0 219.7 465.7 General and administrative expenses 110.8 197.2 308.0 Underwriting (loss) (27.7) (59.3) (87.0) Corporate expenses (70.2) Non-operating expenses (1) (32.7) Net investment income 154.6 Realized and unrealized investment gains 98.5 Realized and unrealized investment losses (27.4) Change in fair value of derivatives (65.1) Interest expense (33.9) Net realized and unrealized foreign exchange (losses) (13.8) Other income 49.8 Other expenses (10.8) (Loss) before income taxes (38.0) Income tax (expense) (18.4) Net (loss) $ (56.4) Net reserves for loss and loss adjustment expenses $ 2,095.7 $ 1,874.4 $ 3,970.1 Ratios Loss ratio 74.4 % 71.1 % 72.8 % Acquisition cost ratio 19.1 17.7 18.4 General and administrative expense ratio 8.6 15.9 12.2 Expense ratio 27.7 33.6 30.6 Combined ratio 102.1 % 104.7 % 103.4 % ________________ (1) Non-operating expenses includes $18.2 million of expenses related to severance, retention and other costs, $12.9 million of impairment charges related to lease assets as a result of sub-leasing certain office space and $1.6 million of amortization of intangible assets and other non-operating expenses. Geographical Areas . The following summary presents the Company’s gross written premiums based on the location of the insured risk for the twelve months ended December 31, 2022, 2021 and 2020. For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Australia/Asia $ 257.5 $ 275.8 $ 259.7 Europe 194.5 140.6 92.5 United Kingdom 485.8 393.2 369.0 United States & Canada (1) 2,715.7 2,301.8 2,267.5 Worldwide excluding United States (2) 24.2 31.5 23.1 Worldwide including United States (3) 541.7 592.2 501.2 Other (4) 119.3 203.3 185.5 Total $ 4,338.7 $ 3,938.4 $ 3,698.5 ________________ (1) “United States and Canada” comprises individual policies that insure risks specifically in the United States and/or Canada, but not elsewhere. (2) “Worldwide excluding the United States” consists of individual policies that insure global risks with the specific exclusion of the United States. (3) “Worldwide including the United States” consists of individual policies that insure global risks with the specific inclusion of the United States. (4) “Other” comprises individual policies that insure risk in other countries including, but not limited to, the Caribbean, South America and Middle East. Segment Reporting The Company manages its underwriting operations as two business segments: Aspen Reinsurance and Aspen Insurance. The Company has determined its reportable segments by taking into account the manner in which management makes operating decisions and assesses operating performance. Profit or loss for each of the Company’s business segments is measured by underwriting income or loss. Underwriting profit is the excess of net earned premiums over the sum of losses and loss expenses, acquisition costs and general and administrative expenses. Underwriting income or loss provides a basis for management to evaluate the segment’s underwriting performance. Reinsurance Segment. The reinsurance segment consists of property catastrophe reinsurance, other property reinsurance, casualty reinsurance and specialty reinsurance. For a more detailed description of this business segment, refer to “Business—Our Business—Reinsurance” in this prospectus. Insurance Segment. The insurance segment consists of first party insurance, specialty insurance, casualty and liability insurance and financial and professional lines insurance. Additionally, the insurance segment includes Aspen Underwriting Limited’s participation as a corporate member in Carbon Syndicate 4747 (“Carbon Syndicate”). For a more detailed description of this business segment, refer to “Business—Our Business—Insurance” in this prospectus. Non-underwriting Disclosures. The Company provides additional disclosures for corporate and other (non-operating) income and expenses. Corporate and other income and expenses include: corporate expenses, net investment income, net realized and unrealized investment gains or losses, other strategic and other costs, changes in fair value of derivatives or the loan notes issued by variable interest entities, interest expenses, net realized and unrealized foreign exchange gains or losses, asset impairments and income taxes. These income and expense items are not allocated to the Company’s business segments as they are not directly related to the Company’s business segment operations and is consistent with how management measures the performance of its segments. The Company does not allocate its assets by business segment. The Company uses underwriting ratios as measures of performance. The loss ratio is the ratio of losses and loss adjustment expenses to net earned premiums. The acquisition cost ratio is the ratio of acquisition costs to net earned premiums. The general and administrative expense ratio is the ratio of general and administrative expenses to net earned premiums. The combined ratio is the sum of the loss ratio, the acquisition cost ratio and the general and administrative expense ratio. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for six months ended June 30, 2023 and 2022: Six Months Ended June 30, 2023 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 875.7 $ 1,249.5 $ 2,125.2 Net written premiums 605.0 745.5 1,350.5 Net earned premiums 572.0 715.4 1,287.4 Underwriting Expenses Losses and loss adjustment expenses 297.2 419.9 717.1 Acquisition costs 105.7 87.2 192.9 General and administrative expenses 58.4 110.6 169.0 Underwriting income 110.7 97.7 208.4 Corporate and other expenses (1) (53.1) Non-operating expenses (10.6) Net investment income 129.4 Realized and unrealized investment gains 36.1 Realized and unrealized investment losses (18.1) Change in fair value of derivatives 19.6 Interest expense (42.9) Net realized and unrealized foreign exchange losses (13.7) Income before income taxes 255.1 Income tax (expense) (36.2) Net income $ 218.9 Net reserves for loss and loss adjustment expenses $ 1,441.2 $ 1,641.7 $ 3,082.9 Ratios Loss ratio 52.0 % 58.7 % 55.7 % Acquisition cost ratio 18.5 12.2 15.0 General and administrative expense ratio 10.2 15.5 13.1 Expense ratio 28.7 27.7 28.1 Combined ratio 80.7 % 86.4 % 83.8 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately. Six Months Ended June 30, 2022 Reinsurance Insurance Total ( $ in millions) Underwriting Revenues Gross written premiums $ 1,045.6 $ 1,305.7 $ 2,351.3 Net written premiums 783.7 722.4 1,506.1 Net earned premiums 600.8 726.4 1,327.2 Underwriting Expenses Losses and loss adjustment expenses 369.0 398.7 767.7 Acquisition costs 124.1 92.4 216.5 General and administrative expenses 69.7 116.8 186.5 Underwriting income 38.0 118.5 156.5 Corporate and other expenses (1) (37.5) Non-operating expenses (3.6) Net investment income 88.7 Realized and unrealized investment gains 2.5 Realized and unrealized investment losses (128.9) Realized loss on debt extinguishment — Change in fair value of loan notes issued by variable interest entities — Change in fair value of derivatives (84.9) Interest expense (9.1) Net realized and unrealized foreign exchange gains 75.2 Other income 2.9 Other expenses (8.7) Income before income taxes 53.1 Income tax (expense) (4.7) Net income $ 48.4 Net reserves for loss and loss adjustment expenses $ 1,190.4 $ 1,314.9 $ 2,505.3 Ratios Loss ratio 61.4 % 54.9 % 57.8 % Acquisition cost ratio 20.7 12.7 16.3 General and administrative expense ratio 11.6 16.1 14.1 Expense ratio 32.3 28.8 30.4 Combined ratio 93.7 % 83.7 % 88.2 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately.

Investments

Investments	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Income Statement Net investment income . The following table summarizes investment income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Fixed income securities — Available for sale $ 95.6 $ 87.2 $ 106.5 Fixed income securities — Trading 57.0 30.2 32.8 Short-term investments — Available for sale 0.6 0.1 0.8 Short-term investments — Trading 0.1 — 0.5 Fixed term deposits (included in cash and cash equivalents) 6.6 0.7 6.4 Catastrophe bonds — Trading 0.3 0.9 1.4 Privately-held investments — Trading 24.3 18.2 20.9 Other investments, at fair value (1) 13.9 21.9 (2.0) Total 198.4 159.2 167.3 Investment expenses (10.3) (11.7) (12.7) Net investment income $ 188.1 $ 147.5 $ 154.6 ________________ (1) Other investments represents the Company’s investments in real estate funds and other special purpose vehicles. The movement in the year represents the change in fair value of the investment and has been included as part of our investment income. The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 2.9 $ 22.7 $ 68.8 Fixed income securities — gross realized (losses) (58.4) (3.6) (1.8) Short-term investments — gross realized gains 1.0 2.0 0.5 Short-term investments — gross realized (losses) (0.5) (0.8) (0.4) Net change in expected credit (losses)/gains (5.0) (2.5) 0.4 Trading: Fixed income securities — gross realized gains 0.2 12.2 18.2 Fixed income securities — gross realized (losses) (1.8) (2.0) (3.8) Short-term investments — gross realized gains — 0.1 0.2 Short-term investments — gross realized (losses) — (0.3) (0.3) Privately-held investments — gross realized gains 0.7 0.6 — Privately-held investments — gross realized (losses) (0.1) (13.8) — Privately-held investments — net unrealized (losses)/gains (2.5) 18.1 (20.4) Catastrophe bonds — net unrealized gains/(losses) 0.2 (0.8) — Fixed income securities — net unrealized (losses) (113.9) (23.4) — Investments — equity method: Gross realized and unrealized gains/(losses) in MVI — 0.1 (0.4) Gross unrealized (losses)/gains in Multi-Line Reinsurer (0.4) 0.2 — Gross realized and unrealized (losses)/gains in Digital Risk — — (0.3) Gross realized gain on sale of Bene — — 1.8 Gross realized gain on sale of Crop Re — — 8.6 Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations $ (177.6) $ 8.8 $ 71.1 Change in available for sale net unrealized (losses)/gains: Fixed income securities (391.7) (157.6) 108.5 Income tax benefit/(expense) 23.9 (0.3) (0.5) Total change in net unrealized (losses)/gains, net of taxes recorded in other comprehensive income $ (367.8) $ (157.9) $ 108.0 Balance Sheet Fixed Income Securities and Short-Term Investments — Available For Sale. The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 __________________ (1) For the twelve months ended December 31, 2022, there was an increase in the CECL allowance on available-for-sale investments of $5.0 million (December 31, 2021 — $2.5 million decrease). As at December 31, 2021 Cost or Gross Gross Allowance Fair Market ($ in millions) U.S. government $ 1,066.2 $ 24.0 $ (5.9) $ — $ 1,084.3 U.S. agency 20.7 0.8 — — 21.5 Municipal 81.2 2.0 (0.5) (0.1) 82.6 Corporate 2,176.1 47.5 (13.0) (2.3) 2,208.3 Non-U.S. government-backed corporate 138.5 0.2 (1.9) — 136.8 Non-U.S. government 250.8 1.4 (1.2) (0.3) 250.7 Asset-backed 0.5 — — — 0.5 Non-agency commercial mortgage-backed 6.6 0.3 — — 6.9 Agency mortgage-backed 1,082.9 19.1 (12.0) — 1,090.0 Total fixed income securities — Available for sale 4,823.5 95.3 (34.5) (2.7) 4,881.6 Total short-term investments — Available for sale 10.1 — — — 10.1 Total $ 4,833.6 $ 95.3 $ (34.5) $ (2.7) $ 4,891.7 Fixed Income Securities, Short Term Investments, Equities, Catastrophe Bonds and Privately-held Investments — Trading. The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 $ 0.6 $ (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Equity securities 6.6 — — 6.6 Short-term investments 25.6 — — 25.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 As at December 31, 2021 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 115.9 $ 0.6 $ (0.2) $ 116.3 Municipal 3.9 0.1 — 4.0 Corporate 95.7 1.9 (0.8) 96.8 High yield loans 77.2 0.1 (0.4) 76.9 Non-U.S. government-backed corporate 13.3 — (0.2) 13.1 Non-U.S. government 34.9 — (0.4) 34.5 Asset-backed 784.3 3.3 (1.9) 785.7 Agency mortgage-backed 30.3 0.2 (0.3) 30.2 Total fixed income securities — Trading 1,155.5 6.2 (4.2) 1,157.5 Short-term investments — Trading 2.0 — — 2.0 Catastrophe bonds — Trading 5.3 — (1.9) 3.4 Privately-held investments — Trading Commercial mortgage loans $ 212.0 0.4 (0.9) $ 211.5 Middle market loans 66.9 — (1.5) 65.4 Asset-backed securities 26.8 — (0.2) 26.6 Equity securities 3.5 0.1 — 3.6 Total privately-held investments — Trading 309.2 0.5 (2.6) 307.1 Total Investments — Trading $ 1,472.0 $ 6.7 $ (8.7) $ 1,470.0 Catastrophe bonds. The Company has invested in catastrophe bonds with a total value of $2.9 million as at December 31, 2022 (December 31, 2021 — $3.4 million). The bonds are either zero-coupon notes or receive quarterly interest payments based on variable interest rates with scheduled maturities ranging from 2023 to 2026. The redemption value of the bonds will adjust based on the occurrence or aggregate occurrence of a covered event, such as windstorms and earthquakes in the United States, Canada, the North Atlantic, South America, Europe, Japan or Australia. Privately-held investments. The Company has invested in privately-held investments, which primarily include commercial mortgage loans of $312.1 million and middle market loans of $106.9 million as at December 31, 2022 (December 31, 2021 — commercial mortgage loans of $211.5 million; middle market loans of $65.4 million). Privately-held investments also includes investments in asset-backed securities, equity securities and other short term investments. Commercial Mortgage Loans . The commercial mortgage loans are related to investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, property type, and security to determine that properties are performing at a consistent and acceptable level to secure the related debt. The following table presents the type of commercial mortgage loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 115.3 36.9 101.6 48.1 Hotels 108.0 34.6 68.8 32.5 Office building 42.1 13.5 33.9 16.0 Other commercial 41.4 13.3 7.2 3.4 Retail 3.3 1.1 — — Industrial 2.0 0.6 — — Total commercial mortgage loans $ 312.1 100 % 211.5 100 % Geographic Region U.S. 269.8 86.4 183.7 86.9 International 42.3 13.6 27.8 13.1 Total commercial mortgage loans $ 312.1 100 % 211.5 100 % The primary credit quality indicator of commercial mortgage loans is loan performance. Non-performing commercial mortgage loans are generally 90 days or more past due. As of December 31, 2022, none of our commercial mortgage loans were non-performing. Loan-to-value and debt service coverage ratios are measures we use to assess the risk and quality of commercial mortgage loans. The loan-to-value ratio is expressed as a percentage of the value of the loan relative to the value of the underlying property. A loan-to-value ratio in excess of 100% indicates the unpaid loan amount exceeds the underlying collateral. The following table represents the loan-to-value ratio of the commercial mortgage loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 41.1 $ — 50% to 60% 248.3 131.2 61% to 70% 22.7 80.3 Commercial mortgage loans $ 312.1 $ 211.5 The debt-service coverage ratio is measured by a property’s net operating income as a multiple of its debt re-payments. A ratio of less than 1.0 reflects a property’s operations is not sufficient to cover its debt payments. The following table represents the debt-service coverage ratio of the commercial mortgage loan portfolio, excluding those that are non-performing and construction loans which are still under development, as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 106.1 $ 66.3 1.00 - 1.20x 186.1 62.4 Less than 1.00x — 18.8 Commercial mortgage loans (1) $ 292.2 $ 147.5 __________________ (1) As at December 31, 2022, we have non-performing loans of $Nil (December 31, 2021 — $Nil) and construction loans of $19.9 million (December 31, 2021 — $64.0 million) which only generate income when the construction is completed. As no income is currently being generated on these loans, they are not included in the table above. The total value of commercial mortgage loans is $312.1 million as at December 31, 2022 (December 31, 2021 — $211.5 million). Middle Market Loans. The middle market loans are investments in senior secured loan positions with full covenants, focused on the middle market in both U.S., Europe and the Caribbean. The middle market loan portfolio is diversified by industry type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, industry and security to determine that loans are performing at a consistent and acceptable level to secure the related debt. The following table presents the type of middle market loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 19.8 18.5 20.9 32.0 Financials 53.1 49.7 6.1 9.3 Industrials 18.7 17.5 18.7 28.5 Consumer discretionary 4.9 4.6 4.3 6.6 Energy 5.7 5.3 5.6 8.6 Consumer staples — — 4.9 7.5 Information technology 4.7 4.4 4.9 7.5 Total middle market mortgage loans $ 106.9 100 % $ 65.4 100 % Geographic Region U.S. 64.1 59.9 56.2 85.9 International 42.8 40.1 9.2 14.1 Total middle market loans $ 106.9 100 % $ 65.4 100 % The primary credit quality indicator of middle market loans is loan performance. Non-performing middle market loans are generally 90 days or more past due. As of December 31, 2022, all of our middle market loans were performing. Loan-to-enterprise-value and fixed charge coverage ratios are measures we use to assess the risk and quality of middle market loans. The loan-to-enterprise-value ratio is expressed as a percentage of the value of the loan relative to the value of the business. A loan-to-enterprise-value ratio in excess of 100% indicates the unpaid loan amount exceeds the value of the underlying business. The following table represents the loan-to-enterprise-value ratio of the middle market loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 63.5 $ 11.0 50% to 60% 16.4 9.2 61% to 70% 27.0 15.8 71% to 80% — 5.6 81% to 100% — 12.0 Greater than 100% — 11.8 Middle market loans $ 106.9 $ 65.4 The fixed charge coverage ratio, based upon the most recent financial statements, is expressed as a percentage of a firm’s earnings plus fixed charges to its fixed charges. Fixed charges include debt repayments, interest and equipment lease expenses. A fixed charge coverage ratio of less than 1.0 indicates a firm’s operations do not generate enough income to cover its fixed charges. The following represents the fixed charge coverage ratio of the middle market loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 95.2 $ 25.8 1.00 - 1.20x 3.8 22.8 Less than 1.00x 7.9 16.8 Middle market loans $ 106.9 $ 65.4 The Company has individually assessed each of the middle market loans with the fixed charge coverage ratio of less than 1.00x. This is mainly due to increased capital investment to support the increased business post COVID-19. These investments have been performing with the fixed charged increasing over the year. Asset-backed securities. Asset-backed securities represent interests in underlying pools of diversified referenced assets that are collateralised and backed by future cash flows and these securities are performing. Global corporate securities. The Global corporates portfolio consists of debt securities with a non-U.S. debt issuer that are backed by the cash flows generated from real estate holdings and these securities are performing. Equity securities. Equity securities consists of a single non-U.S. private issuer that is a special purpose vehicle designed to grant a first lien right to the underlying senior notes. The underlying issuer is a financial services lender to middle market companies and this security is performing. Investments — Equity Method. In January 2015, the Company, along with seven other insurance companies, established a micro-insurance venture consortium and micro-insurance incubator (“MVI”) domiciled in Bermuda. The MVI is a social impact organization that provides micro-insurance products to assist global emerging consumers. In March 2021, the Company committed an additional $0.8 million equity contribution to MVI over a 2 year period and paid $0.4 million in the period ending December 31, 2022 (December 31, 2021 — $0.4 million). On January 1, 2017, the Company purchased through its wholly-owned subsidiary, Aspen U.S. Holdings, Inc. (“Aspen U.S. Holdings”), a 49% share of Digital Risk Resources, LLC (“Digital Re”), a U.S.-based enterprise engaged in the business of developing, marketing and servicing turnkey information security and privacy liability insurance products for a total consideration of $2.3 million. The investment is accounted for under the equity method and adjustments to the carrying value of this investment are made based on the Company’s share of capital, including share of income and expenses. On December 23, 2019, the Company committed $5.0 million as an equity investment in the holding company of a multi-line reinsurer. The strategy for the multi-line reinsurer is to combine a diversified reinsurance business, focused primarily on long-tailed lines of property and casualty business and, potentially to a lesser extent, life business, with a diversified investment strategy. During the period ending December 31, 2022, $1.6 million (December 31, 2021 — $2.5 million) capital was invested in multi-line reinsurer. The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the twelve months ended December 31, 2022 and 2021: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Distribution received — — — — Unrealized (loss)/gain for the twelve months to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investment as at December 31, 2022 0.8 5.2 0.2 6.2 Opening undistributed value of investment as at January 1, 2021 $ — $ 0.5 $ 0.4 $ 0.9 Investment in the period 0.4 2.5 0.3 3.2 Distribution received — — (0.5) (0.5) Unrealized gain for the twelve months to December 31, 2021 0.1 0.2 — 0.3 Closing value of investments at December 31, 2021 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Other Investments. On December 20, 2017, the Company committed to, and during 2018 invested $100.0 million as a limited partner to a real estate fund, classified as other investments. As at December 31, 2022, the current fair value of the fund is $134.6 million (2021 — $129.9 million). On September 30, 2021, the Company committed $20.0 million as a limited partner to a third party managed real estate fund. The Partnership was established to make equity and equity related investments in multifamily and other commercial real estate properties located in the United States and its territories, with the goal of generating superior risk-adjusted returns. The Partnership seeks to acquire commercial real estate assets including real estate assets (or interests therein) that may have management or operational problems and require improvements or lack sufficient capital, including mortgage loans and development or redevelopment properties. On April 1, 2022, the Company committed an additional $10.0 million to the fund. As at December 31, 2022, the current fair value of the fund is $40.6 million (2021 — $21.4 million) and the unfunded commitment is $3.3 million. On April 1, 2022, the Company committed $30.0 million as a limited partner to a related party managed real estate fund. The Partnership was established to pursue investment opportunities to acquire, recapitalize, restructure and reposition real estate assets, portfolios and companies primarily in the United States. As at December 31, 2022, the current fair value of the fund is $25.3 million and the unfunded commitment is $5.3 million. On May 5, 2022, the Company committed $15.0 million as a limited partner to a third party managed infrastructure fund. The Partnership was established to make investments in value added infrastructure investments in environmental services, transportation, communications and digital, energy/energy transition and other infrastructure sectors primarily in North America. As at December 31, 2022, the current fair value of the fund is $8.2 million and the unfunded commitment is $8.4 million. As at December 31, 2022, the aggregate current fair value of the real estate funds investments described above is $221.3 million (2021 — $151.3 million). For further information on the real estate funds, refer to Note 20(a) in these consolidated financial statements, “Commitments and Contingencies.” Fixed income maturities, Available for sale. The scheduled maturity distribution of the Company’s available for sale fixed income securities as at December 31, 2022 and December 31, 2021 is set forth below. Actual maturities may differ from contractual maturities because issuers of securities may have the right to call or prepay obligations with or without call or prepayment penalties. As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6 At December 31, 2021 Amortized Fair Market Average ($ in millions) Due one year or less $ 545.1 $ 549.0 AA- Due after one year through five years 2,057.2 2,087.5 AA- Due after five years through ten years 1,090.5 1,106.3 A+ Due after ten years 40.7 41.4 A- Total — Government and corporate 3,733.5 3,784.2 Non-agency commercial mortgage-backed 6.6 6.9 AA+ Agency mortgage-backed 1,082.9 1,090.0 AA+ Asset-backed 0.5 0.5 AAA Total fixed income securities — Available for sale $ 4,823.5 $ 4,881.6 Guaranteed Investments. As at December 31, 2022 and December 31, 2021, the Company held no investments which are guaranteed by mono-line insurers, excluding those with explicit government guarantees. The Company’s exposure to other third-party guaranteed debt is primarily to investments backed by non-U.S. government guaranteed issuers. Gross unrealized losses, available for sale. The following tables summarize, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Company’s available for sale portfolio as at December 31, 2022 and December 31, 2021: December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166 December 31, 2021 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 309.1 $ (4.0) $ 29.3 $ (1.9) $ 338.4 $ (5.9) 51 U.S. agency 6.1 — — — 6.1 — 5 Municipal 29.7 (0.5) — — 29.7 (0.5) 20 Corporate 804.6 (11.7) 23.6 (1.3) 828.2 (13.0) 400 Non-U.S. government-backed corporate 114.4 (1.9) — — 114.4 (1.9) 10 Non-U.S. government 181.8 (1.2) 3.1 — 184.9 (1.2) 35 Agency mortgage-backed 564.5 (11.6) 16.0 (0.4) 580.5 (12.0) 116 Total fixed income securities — Available for sale 2,010.2 (30.9) 72.0 (3.6) 2,082.2 (34.5) 637 Total short-term investments — Available for sale 4.4 — — — 4.4 — 7 Total $ 2,014.6 $ (30.9) $ 72.0 $ (3.6) $ 2,086.6 $ (34.5) 644 The increase in gross unrealized losses is largely attributable to the impact of rising interest rates on our bond portfolio and mortgage-backed securities. Investments Income Statement Net investment income . The following table summarizes investment income for the six months ended June 30, 2023 and 2022; For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Fixed income securities — Available for sale $ 55.7 $ 44.5 Fixed income securities — Trading 47.8 18.9 Short-term investments — Available for sale 1.6 — Short-term investments — Trading 0.1 — Fixed term deposits (included in cash and cash equivalents) 17.3 0.5 Catastrophe bonds — Trading 1.1 0.1 Privately-held investments — Trading 21.5 8.8 Other investments, at fair value (1) (10.4) 20.7 Total 134.7 93.5 Investment expenses (5.3) (4.8) Net investment income $ 129.4 $ 88.7 __________________ (1) Other investments represents the Company’s investments in real estate, infrastructure and direct lending funds. The movement in the periods represent the change in fair value of the investment and has been included as part of our investment income. The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the six months ended June 30, 2023 and 2022: For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 0.4 $ 1.4 Fixed income securities — gross realized (losses) (6.9) (29.9) Short-term investments — gross realized (losses) (0.2) — Cash and cash equivalents — gross realized gains 0.1 0.9 Cash and cash equivalents — gross realized (losses) (0.1) (0.2) Net change in expected credit gains/(losses) 3.7 (7.7) Trading: Fixed income securities — gross realized gains 0.3 — Fixed income securities — gross realized (losses) (1.1) (0.2) Short-term investments — gross realized gains 0.1 — Short-term investments — gross realized (losses) (0.2) — Privately-held investments — gross realized gains 0.1 0.2 Privately-held investments — net unrealized (losses) (9.0) (1.3) Catastrophe bonds — net unrealized (losses) (0.6) (0.1) Fixed income securities — net unrealized gains/(losses) 31.0 (89.6) Investments — equity method: Net change in realized and unrealized gains in Multi-Line Reinsurer 0.4 0.1 Total net realized and unrealized investment gains/(losses) recorded in the consolidated statement of operations $ 18.0 $ (126.4) Change in available for sale net unrealized gains/(losses): Fixed income securities gains/(losses) 12.3 (316.0) Income tax (expense)/benefit (1.6) 29.5 Total change in net unrealized gains/(losses), net of taxes recorded in other comprehensive income $ 10.7 $ (286.5) Balance Sheet Fixed Income Securities and Short-Term Investments — Available For Sale. The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,064.9 $ — $ (51.1) $ — $ 1,013.8 U.S. agency 8.6 — (0.4) — 8.2 Municipal 159.0 — (8.8) (0.7) 149.5 Corporate 2,031.9 2.4 (155.2) (3.2) 1,875.9 Non-U.S. government-backed corporate 119.6 — (8.7) — 110.9 Non-U.S. government 281.3 — (12.0) (0.1) 269.2 Non-agency commercial mortgage-backed 6.6 — (0.9) — 5.7 Agency mortgage-backed 559.3 — (84.3) — 475.0 Total fixed income securities — Available for sale 4,231.2 2.4 (321.4) (4.0) 3,908.2 Total short-term investments — Available for sale 169.3 — — — 169.3 Total $ 4,400.5 $ 2.4 $ (321.4) $ (4.0) $ 4,077.5 __________________ (1) For the six months ended June 30, 2023, there was a decrease in the CECL allowance on available-for-sale investments of $3.7 million (December 31, 2022 — $5.0 million increase). As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 Fixed Income Securities, Short-Term Investments, Equities, Catastrophe Bonds and Privately-held Investments — Trading . The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 241.9 $ — $ (6.9) $ 235.0 Municipal 3.4 — (0.3) 3.1 Corporate 176.9 0.3 (11.8) 165.4 High yield loans 86.1 1.2 (0.7) 86.6 Non-U.S. government-backed corporate 10.1 — (0.5) 9.6 Non-U.S. government 35.8 — (1.7) 34.1 Asset-backed 975.2 1.0 (51.6) 924.6 Agency mortgage-backed 23.3 — (3.2) 20.1 Total fixed income securities — Trading 1,552.7 2.5 (76.7) 1,478.5 Short-term investments — Trading 11.0 — — 11.0 Catastrophe bonds — Trading 2.4 — — 2.4 Privately-held investments — Trading Commercial mortgage loans $ 305.5 $ 1.3 $ (11.8) $ 295.0 Middle market loans 104.1 — (2.0) 102.1 Asset-backed securities 59.5 — (1.1) 58.4 Global corporate securities 14.9 — (0.1) 14.8 Equity securities 12.1 — — 12.1 Total privately-held investments — Trading 496.1 1.3 (15.0) 482.4 Total Investments — Trading $ 2,062.2 $ 3.8 $ (91.7) $ 1,974.3 As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 0.6 (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Short-term investments 25.6 — — 25.6 Equity securities 6.6 — — 6.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 Catastrophe bonds. The Company has invested in catastrophe bonds with a total value of $2.4 million as at June 30, 2023 (December 31, 2022 — $2.9 million). The bonds are either zero-coupon notes or receive quarterly interest payments based on variable interest rates with scheduled maturities ranging from 2023 to 2026. The redemption value of the bonds will adjust based on the occurrence or aggregate occurrence of a covered event, such as windstorms and earthquakes in the United States, Canada, the North Atlantic, South America, Europe, Japan or Australia. Privately-held investments. The Company has invested in privately-held investments, which primarily include commercial mortgage loans of $295.0 million and middle market loans of $102.1 million as at June 30, 2023 (December 31, 2022 — commercial mortgage loans of $312.1 million; middle market loans of $106.9 million). Privately-held investments also includes investments in asset-backed securities, equity securities and other short-term investments. Commercial Mortgage Loans . The commercial mortgage loans are related to investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, property type, and security to determine that properties are performing at a consistent and acceptable level to secure the related debt. The foll

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2023
Payables and Accruals [Abstract]
Variable Interest Entities	Variable Interest Entities As at December 31, 2022, the Company held an investment in one (December 31, 2021 — one) variable interest entity (“VIE”), namely Peregrine Reinsurance Ltd (“Peregrine”). Peregrine . In November 2016, Peregrine, a subsidiary of the Company, was registered as a segregated accounts company under the Segregated Accounts Companies Act 2000, as amended. As at December 31, 2022, Peregrine had six segregated accounts which were funded by third-party investors, which are not consolidated, and two segregated accounts which are funded by Aspen and are consolidated within the financial statements. The Company has determined that Peregrine has the characteristics of a VIE as addressed by the guidance in ASC 810, Consolidation . The six segregated accounts have not been consolidated as part of the Company’s consolidated financial statements because the Company is not the primary beneficiary of those accounts. The Company has, however, concluded that it is the primary beneficiary of the Peregrine general fund and, similar to prior reporting periods, the results of the Peregrine general fund are included in the Company’s consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s estimates of fair value for financial assets and liabilities are based on the framework established in the fair value accounting guidance included in ASC Topic 820, “ Fair Value Measurements and Disclosures .” The framework prioritizes the inputs, which refer broadly to assumptions market participants would use in pricing an asset or liability, into three levels. The Company considers prices for actively traded securities to be derived based on quoted prices in an active market for identical assets, which are Level 1 inputs in the fair value hierarchy. The majority of these securities are valued using prices supplied by pricing services. The Company considers prices for other securities that may not be as actively traded which are priced via pricing services, vendors and broker-dealers, or with reference to interest rates and yield curves, to be derived based on inputs that are observable for the asset, either directly or indirectly, which are Level 2 inputs in the fair value hierarchy. The majority of these securities are also valued using prices supplied by pricing services. The Company considers securities, other financial instruments, privately-held investments and derivative insurance contracts subject to fair value measurement whose valuation is derived by internal valuation models to be based largely on unobservable inputs, which are Level 3 inputs in the fair value hierarchy. The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Asset-backed — — — — Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Held for trading financial assets, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Privately-held investments trading, at fair value — — 533.0 533.0 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 56.2 — 56.2 Liabilities under derivative contracts — foreign exchange contracts — (3.2) — (3.2) Liabilities under derivative contracts — loss portfolio transfer (2) — — (31.7) (31.7) Total 1,428.7 3,949.6 501.3 6,100.9 ________________ (1) Other investments represents our investments in real estate and other special purpose vehicles and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. At December 31, 2021 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 1,084.3 $ — $ — $ 1,084.3 U.S. agency — 21.5 — 21.5 Municipal — 82.6 — 82.6 Corporate — 2,208.3 — 2,208.3 Non-U.S. government-backed corporate — 136.8 — 136.8 Non-U.S. government 164.4 86.3 — 250.7 Asset-backed — 0.5 — 0.5 Non-agency commercial mortgage-backed — 6.9 — 6.9 Agency mortgage-backed — 1,090.0 — 1,090.0 Total fixed income securities available for sale, at fair value 1,248.7 3,632.9 — 4,881.6 Short-term investments available for sale, at fair value 6.5 3.6 — 10.1 Held for trading financial assets, at fair value U.S. government 116.3 — — 116.3 Municipal — 4.0 — 4.0 Corporate — 96.8 — 96.8 Non-U.S. government-backed corporate — 13.1 — 13.1 High yield loans — 76.9 — 76.9 Non-U.S. government 11.9 22.6 — 34.5 Asset-backed — 785.7 — 785.7 Agency mortgage-backed — 30.2 — 30.2 Total fixed income securities trading, at fair value 128.2 1,029.3 — 1,157.5 Short-term investments trading, at fair value 1.1 0.9 — 2.0 Privately-held investments — — 307.1 307.1 Catastrophe bonds trading, at fair value — 3.4 — 3.4 Other investments (1) — — — 151.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 12.9 — 12.9 Liabilities under derivative contracts — foreign exchange contracts — (13.3) — (13.3) Total $ 1,384.5 $ 4,669.7 $ 307.1 $ 6,512.6 ________________ (1) Other investments represents our investments in real estate funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” Transfers of assets into or out of a particular level are recorded at their fair values as of the end of each reporting period consistent with the date of the determination of fair value. During the twelve months ended December 31, 2022, $Nil ( December 31, 2021 — $19.5 million was transferred into Level 3) was transferred in or out of Level 3. As at December 31, 2022, there were privately-held investments carried at $533.0 million (December 31, 2021 — $307.1 million) classified as Level 3. As a result of loans sold by Aspen and loans repaid to Aspen by borrowers, a net settlement of $147.4 million occurred during the year. Additionally as at December 31, 2022, there was an embedded derivative as part of the loss portfolio transfer agreement worth $31.7 million classified as Level 3. The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Lev el 3 inputs for the twelve months ended December 31, 2022 and December 31, 2021: Twelve Months Ended December 31, 2022 Balance at beginning of year Purchases and issuances Transfers in/(out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of year Change in unrealized investment gains (losses) relating to assets held at end of year Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Liabilities under derivative contracts - loss $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Twelve Months Ended December 31, 2021 Assets Privately-held investments — trading Commercial mortgage loans $ 163.6 $ 169.9 $ — $ (122.5) $ 0.5 $ 211.5 $ (0.5) Middle market loans 112.1 5.6 — (56.1) 3.7 65.3 (1.5) Asset-backed securities 18.6 10.0 — (1.8) (0.1) 26.7 (0.2) Equity securities 5.0 0.1 — (1.6) 0.1 3.6 — Preference shares — 19.5 (19.5) — — — — Total Level 3 assets $ 299.3 $ 205.1 $ (19.5) $ (182.0) $ 4.2 $ 307.1 $ (2.2) Valuation of Fixed Income Securities . The Company’s fixed income securities are classified as either available for sale or trading and are reported at fair value. As at December 31, 2022 and December 31, 2021, the Company’s fixed income securities were valued by pricing services or broker-dealers using standard market conventions. The market conventions utilize market quotations, market transactions in comparable instruments and various relationships between instruments including, but not limited to, yield to maturity, dollar prices and spread prices in determining value. Independent Pricing Services. The underlying methodology used to determine the fair value of securities in the Company’s available for sale and trading portfolios is by the pricing services. Pricing services will gather observable pricing inputs from multiple external sources, including buy and sell-side contacts and broker-dealers, in order to develop their internal prices. Pricing services provide pricing for less complex, liquid securities based on market quotations in active markets. Pricing services supply prices for a broad range of securities including those for actively traded securities, such as Treasury and other Government securities, in addition to those that trade less frequently or where valuation includes reference to credit spreads, pay down and pre-pay features and other observable inputs. These securities include Government agency, municipals, corporate and asset-backed securities. For securities that may trade less frequently or do not trade on a listed exchange, these pricing services may use matrix pricing consisting of observable market inputs to estimate the fair value of a security. These observable market inputs include reported trades, benchmark yields, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, and industry and economic factors. Additionally, pricing services may use a valuation model such as an option adjusted spread model commonly used for estimating fair values of mortgage-backed and asset-backed securities. The Company does not derive dollar prices using an index as a pricing input for any individual security. Broker-Dealers. The Company obtains quotes from broker-dealers who are active in the corresponding markets when prices are unavailable from independent pricing services or index providers. Generally, broker-dealers value securities through their trading desks based on observable market inputs. Their pricing methodologies include mapping securities based on trade data, bids or offers, observed spreads and performance of newly issued securities. They may also establish pricing through observing secondary trading of similar securities. Quotes from broker-dealers are non-binding. The Company obtains prices for all of its fixed income investment securities via its third-party accounting service provider, and in the majority of cases receiving a number of quotes so as to obtain the most comprehensive information available to determine a security’s fair value. A single valuation is applied to each security based on the vendor hierarchy maintained by the Company’s third-party accounting service provider. As at December 31, 2022, the Company obtained an average of 2.9 quotes per fixed income investment compared to 3.0 quotes at December 31, 2021. The Company, in conjunction with its third-party accounting service provider, obtains an understanding of the methods, models and inputs used by the third-party pricing service and index providers to assess the ongoing appropriateness of vendors’ prices. The Company and its third-party accounting service provider also have controls in place to validate that amounts provided represent fair values. Processes to validate and review pricing include, but are not limited to: • quantitative analysis (e.g., comparing the quarterly return for each managed portfolio to its target benchmark, with significant differences identified and investigated); • comparison of market values obtained from pricing services and broker-dealers against alternative price sources for each security where further investigation is completed when significant differences exist for pricing of individual securities between pricing sources; • initial and ongoing evaluation of methodologies used by outside parties to calculate fair value; and • comparison of the fair value estimates to the Company’s knowledge of the current market. Prices obtained from pricing services and broker-dealers are not adjusted by us; however, prices provided by a pricing service, or broker-dealer in certain instances may be challenged based on market or information available from internal sources, including those available to the Company’s third-party investment accounting service provider. Subsequent to any challenge, revisions made by the pricing service or broker-dealer to the quotes are supplied to the Company’s investment accounting service provider. Management reviews the vendor hierarchy maintained by the Company’s third-party accounting service provider in order to determine which price source provides the most appropriate fair value (i.e., a price obtained from a pricing service with more seniority in the hierarchy will be used over a less senior one in all cases). The hierarchy level assigned to each security in the Company’s available for sale and trading portfolios is based upon its assessment of the transparency and reliability of the inputs used in the valuation as of the measurement date. The hierarchy of pricing services is determined using various qualitative and quantitative points arising from reviews of the vendors conducted by the Company’s third-party accounting service provider. Vendor reviews include annual due diligence meetings with index providers and pricing services vendors covering valuation methodology, operational walkthroughs and legal and compliance updates. Fixed Income Securities . Fixed income securities are traded on the over-the-counter (“OTC”) market based on prices provided by one or more market makers in each security. Securities such as U.S. Government, U.S. Agency, Foreign Government and investment grade corporate bonds have multiple market makers in addition to readily observable market value indicators such as expected credit spread, except for Treasury securities, over the yield curve. The Company uses a variety of pricing sources to value fixed income securities including those securities that have pay down/prepay features such as mortgage-backed securities and asset-backed securities in order to ensure fair and accurate pricing. The fair value estimates for the investment grade securities in the Company’s portfolio do not use significant unobservable inputs or modeling techniques. U.S. Government and Agency Securities. U.S. government and agency securities consist primarily of bonds issued by the U.S. Treasury and corporate debt issued by agencies such as the Federal National Mortgage Association (“FNMA”), the Federal Home Loan Mortgage Corporation (“FHLMC”) and the Federal Home Loan Bank. As the fair values of U.S. Treasury securities are based on unadjusted market prices in active markets, they are classified within Level 1. The fair values of U.S. government agency securities are priced using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of U.S. government agency securities are classified within Level 2. Municipal Securities. The Company’s municipal portfolio consist of bonds issued by U.S. domiciled state and municipality entities. The fair value of these securities is determined using spreads obtained from broker-dealers, trade prices and the new issue market which are Level 2 inputs in the fair value hierarchy. Consequently, these securities are classified within Level 2. Non-U.S. Government. The issuers for securities in this category are non-U.S. governments and their agents including, but not limited to, the U.K., Australia, Canada, France and Germany. The fair values of certain non-U.S. government bonds, primarily sourced from international indices, are based on unadjusted market prices in active markets and are therefore classified within Level 1. The remaining non-U.S. government bonds are classified within level 2 as they are not actively traded. The fair values of the non-U.S. agency securities, again primarily sourced from international indices, are priced using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of non-U.S. agency securities are classified within Level 2. In addition, foreign government securities include a portion of the Emerging Market Debt (“EMD”) portfolio which is also classified within Level 2. Corporate. Corporate securities consist primarily of short-term, medium-term and long-term debt issued by U.S. and foreign corporations covering a variety of industries and are generally priced by index providers and pricing vendors. Some issuers may participate in government programs which guarantee timely payment of principal and interest in the event of a default. The fair values of these securities are generally determined using the spread above the risk-free yield curve. Inputs used in the evaluation of these securities include credit data, interest rate data, market observations and sector news, broker-dealer quotes and trade volumes. In addition, corporate securities include a portion of the EMD portfolio. The Company classifies these securities across Level 1 and 2, with majority of them being in Level 1. Mortgage-backed Securities. Residential and commercial mortgage-backed securities consist of bonds issued by the Government National Mortgage Association, the FNMA and the FHLMC as well as private non-agency issuers. The fair values of these securities are determined through the use of a pricing model (including Option Adjusted Spread) which uses prepayment speeds and spreads to determine the appropriate average life of the mortgage-backed security. These spreads are generally obtained from broker-dealers, trade prices and the new issue market. As the significant inputs used to price mortgage-backed securities are observable market inputs, these securities are classified within Level 2. Asset-backed securities. Asset-backed securities are securities backed by notes or receivables against assets other than real estate. The underlying collateral for the Company’s asset-backed securities consists mainly of student loans, automobile loans and credit card receivables. These securities are primarily priced by index providers and pricing vendors. Inputs to the valuation process include broker-dealer quotes and other available trade information, prepayment speeds, interest rate data and credit spreads. The Company classifies these securities within Level 2. Privately-Held Investments. Privately-held investments are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models. These models include inputs that are specific to each investment. The inputs used in the fair value measurements include dividend or interest rates and appropriate discount rates. The selection of an appropriate discount rate is judgmental and is the most significant unobservable input used in the valuation of these securities. A significant increase (decrease) in this input in isolation could result in significantly lower (higher) fair value measurement for privately-held investments. In order to assess the reasonableness of the inputs the Company uses in the discounted cash flow models, the Company maintains an understanding of current market conditions, issuer specific information that may impact future cash flows as well as collaboration with independent vendors for most securities to assess the reasonableness of the discount rate being used. Commercial mortgage loans. Commercial mortgage loans consists in investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. Commercial Mortgage Loans are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models and are classified as Level 3. Middle market loans . The middle market loans consist in investments in senior secured loan positions with full covenants, focused on the middle market in both U.S., Europe and the Caribbean. The middle market loan portfolio is diversified by industry type, geographic region and issuer to reduce risks. Middle Market Loans are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models and are classified as Level 3. Asset-backed securities . Asset-backed securities represent interests in underlying pools of diversified referenced assets that are collateralised and backed by future cash flows and these securities are performing. The fair values of these securities are determined by using discounted cash flow models and are classified as Level 3. Global corporate securities. The global corporates portfolio consists of debt securities with a non-U.S. debt issuer that are backed by the cash flows generated from real estate holdings and these securities are performing. The fair value of these securities are determined by using discounted cash flow models and are classified as Level 3. Equity securities. Equity securities consists of a single non-U.S. based issuer that is a special purpose vehicle designed to grant a first lien right to the underlying senior notes within the structure. The underlying issuer is a financial services lender to middle market companies and this security is performing. The valuation of the investments is DCF and the securities are classified as Level 3. Short-term investments. Short-term investments consist of highly liquid debt securities with a maturity greater than three months but less than one year from the date of purchase. Short-term investments are classified as either trading or available for sale according to the facts and circumstances of the investment held. Short-term investments are valued in a manner similar to the Company’s fixed maturity investments and are classified within Levels 1 and 2. The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at December 31, 2022: At December 31, 2022 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 200.7 Discounted cash flow Discount rate 3.9 % 9.4 % 5.3 % Commercial mortgage loans 85.8 Transaction Value n/a n/a n/a n/a Commercial mortgage loans 25.6 Liquidation method n/a n/a n/a n/a Middle market loans 106.9 Discounted cash flow Discount rate 7.4 % – 18.5 % 9.9 % Asset-backed securities 66.8 Discounted cash flow Discount rate 5.8 % – 9.3 % 6.7 % Global corporate securities 15.0 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Equity securities 5.3 Discounted cash flow Discount rate 9.0 % – 12.5 % 9.1 % Equity securities 1.3 Transaction Value n/a n/a n/a n/a Short-term investments 25.6 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Total $ 533.0 Catastrophe Bonds. Catastrophe bonds are variable rate fixed income instruments with redemption values adjusted based on the occurrence of a covered event, usually windstorms and earthquakes. Catastrophe bonds are classified as trading and reported at fair value. Catastrophe bonds are priced using an average of multiple broker-dealer quotes and as such, are considered Level 2. Foreign Exchange Contracts. The foreign exchange contracts which the Company uses to mitigate currency risk are characterized as OTC due to their customized nature and the fact that they do not trade on a major exchange. These instruments trade in a very deep liquid market, providing substantial price transparency and accordingly are classified as Level 2. Liabilities under derivative contracts - loss portfolio transfer. LPT embedded derivative is valued in a Black-Scholes framework. The two primary inputs of this policy are expected claim settlement patterns and expected return of the investment portfolio above a fixed minimum rate over the specified time horizon. The expected claim settlement pattern is determined on an actuarial basis for the cohort of business within scope of the LPT and is consistent with the patterns used in the valuation of technical provisions. The expected return of the investment portfolio, above a fixed minimum rate, directly impacts on the LPT derivative valuation and is subject to changes in the market conditions. In order to assess the reasonableness of the inputs, the company updates the expected claim settlement patterns on a regular basis whilst maintaining an understanding of the current market conditions. Other investments. The Company’s other investments represent our investments in real estate funds and other special purpose vehicles. Adjustments to the fair values are made based on the net asset value of the investments. The net valuation criteria established by the manager of such investments are established in accordance with the governing documents and the asset manager’s valuation guidelines, which include: the discounted cash flows method and the performance multiple approach, which uses a multiple derived from market data of comparable companies or assets to produce operating performance metrics. Alternative valuation methodologies may be employed for investments with unusual characteristics. Fair Value Measurements The Company’s estimates of fair value for financial assets and liabilities are based on the framework established in the fair value accounting guidance included in ASC Topic 820, “ Fair Value Measurements and Disclosures .” The framework prioritizes the inputs, which refer broadly to assumptions market participants would use in pricing an asset or liability, into three levels. The Company considers prices for actively traded securities to be derived based on quoted prices in an active market for identical assets, which are Level 1 inputs in the fair value hierarchy. The majority of these securities are valued using prices supplied by pricing services. The Company considers prices for other securities that may not be as actively traded which are priced via pricing services, vendors and broker-dealers, or with reference to interest rates and yield curves, to be derived based on inputs that are observable for the asset, either directly or indirectly, which are Level 2 inputs in the fair value hierarchy. The majority of these securities are also valued using prices supplied by pricing services. The Company considers securities, other financial instruments, privately-held investments and derivative insurance contracts subject to fair value measurement whose valuation is derived by internal valuation models to be based largely on unobservable inputs, which are Level 3 inputs in the fair value hierarchy. The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 1,013.8 $ — $ — $ 1,013.8 U.S. agency — 8.2 — 8.2 Municipal — 149.5 — 149.5 Corporate — 1,875.9 — 1,875.9 Non-U.S. government-backed corporate — 110.9 — 110.9 Non-U.S. government 192.7 76.5 — 269.2 Non-agency commercial mortgage-backed — 5.7 — 5.7 Agency mortgage-backed — 475.0 — 475.0 Total fixed income securities available for sale, at fair value 1,206.5 2,701.7 — 3,908.2 Short-term investments available for sale, at fair value 169.2 0.1 — 169.3 Fixed income securities, trading, at fair value 235.0 — — 235.0 Municipal — 3.1 — 3.1 Corporate — 165.4 — 165.4 Non-U.S. government-backed corporate — 9.6 — 9.6 High yield loans — 86.6 — 86.6 Non-U.S. government 12.7 21.4 — 34.1 Asset-backed — 924.6 — 924.6 Agency mortgage-backed — 20.1 — 20.1 Total fixed income securities trading, at fair value 247.7 1,230.8 — 1,478.5 Short-term investments trading, at fair value 9.1 1.9 — 11.0 Privately-held investments trading, at fair value — — 482.4 482.4 Catastrophe bonds trading, at fair value — 2.4 — 2.4 Other investments (1) — — — 213.4 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 17.2 — 17.2 Derivative liabilities — foreign exchange contracts — (13.4) — (13.4) Derivative liabilities — loss portfolio transfer (2) — — (23.4) (23.4) Total 1,632.5 3,940.7 459.0 6,245.6 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Fixed income securities, trading, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Privately-held investments — — 533.0 533.0 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 56.2 — 56.2 Derivative liabilities — foreign exchange contracts — (3.2) — (3.2) Derivative liabilities — loss portfolio transfer — — (31.7) (31.7) Total $ 1,428.7 $ 3,949.6 $ 501.3 $ 6,100.9 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictio

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2023
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The Company purchases retrocession and reinsurance to limit and diversify the Company’s risk exposure and to increase its own insurance and reinsurance underwriting capacity. These agreements provide for recovery of losses and loss adjustment expenses from reinsurers. The Company remains liable to the extent that reinsurers do not meet their obligations under these agreements. In line with its risk management objectives, the Company evaluates the financial condition of its reinsurers and monitors concentrations of credit risk. Balances pertaining to reinsurance transactions are reported “gross” on the consolidated balance sheet, meaning that reinsurance recoverable on unpaid losses and ceded unearned premiums are not deducted from insurance reserves but are recorded as assets. For more information on reinsurance recoverables, refer to Note 21, “Concentrations of Credit Risk — Reinsurance recoverables” and Note 10, “Reserves for Losses and Loss Adjustment Expenses” of these consolidated financial statements. The effect of assumed and ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the twelve months ended December 31, 2022, 2021 and 2020 was as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Premiums written: Direct $ 2,531.7 $ 2,341.4 $ 2,042.1 Assumed 1,807.0 1,597.0 1,656.4 Ceded (1,442.7) (1,350.7) (1,120.7) Net premiums written $ 2,896.0 $ 2,587.7 $ 2,577.8 Premiums earned: Direct $ 2,370.8 $ 2,139.1 $ 2,026.4 Assumed 1,617.2 1,479.2 1,612.0 Ceded (1,299.3) (1,207.8) (1,110.9) Net premiums earned $ 2,688.7 $ 2,410.5 $ 2,527.5 Insurance losses and loss adjustment expenses: Direct $ 1,574.2 $ 1,499.8 $ 1,479.6 Assumed 939.5 1,000.6 1,134.5 Ceded (833.7) (807.1) (773.3) Net insurance losses and loss adjustment expenses $ 1,680.0 $ 1,693.3 $ 1,840.8 On January 10, 2022, Aspen Holdings and certain of its subsidiaries (“Aspen”) entered into an Amended and Restated Reinsurance Agreement with a subsidiary of Enstar Group Limited (together, “Enstar”) (the “LPT”), which amended and restated the Adverse Development Cover Agreement, dated as of March 2, 2020, previously entered into between Enstar and Aspen Group (the “Original Agreement)”. Under the terms of the LPT, Enstar’s subsidiary will reinsure net losses incurred on or prior to December 31, 2019 on all of Aspen’s net loss reserves of $3,120.0 million as of September 30, 2021. The LPT provides for a limit of $3,570.0 million in consideration for a premium of $3,160.0 million. The amount of net loss reserves ceded, as well as the premium and limit amounts provided under the LPT, was adjusted for claims paid between October 1, 2021 and the closing date of the transaction. The premium includes $770 million of premium previously paid with respect to reserves ceded under the Original Agreement, which will continue to be held in trust accounts to secure the Enstar subsidiary’s obligations under the LPT. The incremental new premium will initially be held in funds withheld accounts in their original currencies maintained by Aspen but will be released to the trust accounts maintained by the Enstar subsidiary no later than September 30, 2025. The funds withheld by Aspen will be credited with interest at an annual rate of 1.75% plus, for periods after October 1, 2022, an additional amount equal to 50% of the amount by which the total return on Aspen’s investments and cash and cash equivalents exceeds 1.75%. Under the LPT, the Enstar subsidiary assumed claims control, pursuant to the provisions of an administrative services agreement subsequently entered into between the parties on June 30, 2022. Current expected loss model (“CECL”) . On June 16, 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses (Topic 326) ” which introduced a new impairment model, known as the current expected loss model (“CECL”), which is based on expected losses rather than incurred losses. Following the adoption of CECL with effect from January 1, 2020, the Company recognized a reduction in the Company’s reinsurance recoverables by $3.7 million as at December 31, 2022 (2021 — $3.3 million). For the twelve months ended December 31, 2022 there was an increase in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2021 — $0.5 million decrease). Reinsurance The Company purchases retrocession and reinsurance to limit the Company’s risk exposure and to increase its own insurance and reinsurance underwriting capacity. These agreements provide for recovery of losses and loss adjustment expenses from reinsurers. The Company remains liable to the extent that reinsurers do not meet their obligations under these agreements. In line with its risk management objectives, the Company evaluates the financial condition of its reinsurers and monitors concentrations of credit risk. Balances pertaining to reinsurance transactions are reported “gross” on the consolidated balance sheet, meaning that reinsurance recoverable on unpaid losses and ceded unearned premiums are not deducted from insurance reserves but are recorded as assets. For more information on reinsurance recoverables, refer to Note 13, “Concentrations of Credit Risk —Reinsurance recoverables” and Note 8, “Reserves for Losses and Loss Adjustment Expenses” of these unaudited condensed consolidated financial statements. The effect of ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the six months ended June 30, 2023 and 2022 was as follows: Six Months Ended June 30, 2023 2022 ($ in millions) Premiums written: Insurance $ 1,249.5 $ 1,305.7 Reinsurance 875.7 1,045.6 Ceded (774.7) (845.2) Net premiums written $ 1,350.5 $ 1,506.1 Premiums earned: Insurance $ 1,203.6 $ 1,171.5 Reinsurance 755.7 776.9 Ceded (671.9) (621.2) Net premiums earned $ 1,287.4 $ 1,327.2 Insurance losses and loss adjustment expenses: Insurance $ 691.7 $ 719.2 Reinsurance 353.4 402.4 Ceded (328.0) (353.9) Net insurance losses and loss adjustment expenses $ 717.1 $ 767.7

Derivative Contracts

Derivative Contracts	6 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Contracts	Derivative Contracts The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at December 31, 2022 and 2021: As at December 31, 2022 As at December 31, 2021 Derivatives Not Designated as Hedging Instruments Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivatives at Fair Value $ 945.8 $ 41.9 $ 759.8 $ 12.9 Foreign Exchange Contracts Liabilities under Derivative Contracts $ 729.5 $ (3.2) $ 785.9 $ (12.4) Loss Portfolio Transfer Liability - Embedded Derivative (2) Liabilities under Derivative Contracts — $ (31.7) — — ________________ (1) Fair value is net of $3.7 million of cash collateral (December 31, 2021 — $2.1 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. Refer to Note 7 for further information. As at December 31, 2022 As at December 31, 2021 Derivatives Designated as Hedging Instruments Under ASC 815 Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivatives at Fair Value $ 109.7 $ 14.3 $ — $ — Foreign Exchange Contracts Liabilities under Derivative Contracts $ — $ — $ 143.1 $ (0.9) The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging” for the twelve months ended December 31, 2022 and 2021: Amount of (Loss)/Gain Recognized on Derivatives For the Twelve Months Ended Location of Gain/(Loss) December 31, 2022 December 31, 2021 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives (80.5) (35.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations 5.9 (5.7) Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income 15.4 (6.2) Foreign Exchange Contracts. The Company uses foreign exchange contracts to manage foreign currency risk associated with our operating expenses but also foreign exchange risk associated with net assets or liabilities in currencies other than the U.S. dollar. A foreign exchange contract involves an obligation to purchase or sell a specified currency at a future date at a price set at the time of the contract. Foreign exchange contracts will not eliminate fluctuations in the value of the Company’s assets and liabilities denominated in foreign currencies but rather allow it to establish a rate of exchange for a future point in time. As at December 31, 2022, the Company held foreign exchange contracts that were not designated as hedges under ASC 815 with an aggregate nominal amount of $1,675.3 million (2021 — $1,545.7 million). The foreign exchange contracts are recorded as derivatives at fair value in the consolidated balance sheet with changes recorded as a change in fair value of derivatives in the consolidated statement of operations. For the twelve months ended December 31, 2022, the impact of foreign exchange contracts on net income was a loss of $80.5 million (December 31, 2021 — loss of $35.9 million). As at December 31, 2022, the Company held foreign exchange contracts that were designated as hedges under ASC 815 with an aggregate notional amount of $109.7 million (2021 — $143.1 million). The foreign exchange contracts are recorded as assets or liabilities under derivative contracts in the consolidated balance sheet with the effective portion recorded in other comprehensive income and the ineffective portion recorded as a change in fair value of derivatives in the consolidated statement of operations. The contracts are effective and therefore the movement in other comprehensive income representing the effective portion for the twelve months ended December 31, 2022 was a gain of $15.4 million (December 31, 2021 — loss of $6.2 million). As the foreign exchange contracts settle, the realized gain or loss is reclassified from other comprehensive income into general, administration and corporate expenses of the consolidated statement of operations. For the twelve months ended December 31, 2022, the amount recognized within general, administration and corporate expenses for settled foreign exchange contracts was a realized gain of $5.9 million (December 31, 2021 — loss of $5.7 million). Embedded derivative on loss portfolio contract. The loss portfolio transfer contract includes a funds withheld arrangement that provides returns to the reinsurer based on Aspen’s investment performance, guaranteeing a minimum of 1.75% return. Such funds withheld arrangements are examples of embedded derivatives and therefore this instrument is accounted for as an option-based derivative. For the twelve months ended December 31, 2022, the amount recognized as a change in fair value of derivatives in the consolidated statement of operations is $14.5 million. Derivative Contracts The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Derivatives Not Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivative assets $ 670.6 $ 7.2 $ 945.8 $ 41.9 Foreign Exchange Contracts Derivative liabilities $ 1,213.4 $ (13.4) $ 729.5 $ (3.2) Loss Portfolio Transfer Liability - Embedded Derivative (2) Derivative liabilities — $ (23.4) — (31.7) ________________ (1) Fair value is net of $2.7 million of cash collateral (December 31, 2022 — $3.7 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. As at June 30, 2023 As at December 31, 2022 Derivatives Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivative assets $ 54.7 $ 10.0 $ 109.7 $ 14.3 The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging ” for the six months ended June 30, 2023 and 2022: For the Six Months Ended Location of Gain/(Loss) June 30, 2023 June 30, 2022 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives 19.6 (84.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations (3.7) 2.8 Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income (4.3) (6.4) Foreign Exchange Contracts . The Company uses foreign exchange contracts to manage foreign currency risk associated with our operating expenses but also foreign exchange risk associated with net assets or liabilities in currencies other than the U.S. dollar. A foreign exchange contract involves an obligation to purchase or sell a specified currency at a future date at a price set at the time of the contract. Foreign exchange contracts will not eliminate fluctuations in the value of the Company’s assets and liabilities denominated in foreign currencies but rather allow it to establish a rate of exchange for a future point in time. As at June 30, 2023, the Company held foreign exchange contracts that were not designated as hedges under ASC 815 with an aggregate nominal amount of $1,884.0 million (December 31, 2022 — $1,675.3 million). The foreign exchange contracts are recorded as derivative assets or derivative liabilities in the consolidated balance sheet with changes recorded as a change in fair value of derivatives in the consolidated statement of operations. For the six months ended June 30, 2023, the impact of foreign exchange contracts on net income was a gain of $19.6 million (June 30, 2022 — loss of $84.9 million). As at June 30, 2023, the Company held foreign exchange contracts that were designated as hedges under ASC 815 with an aggregate notional amount of $54.7 million (December 31, 2022 — $109.7 million). The foreign exchange contracts are recorded as derivative assets in the consolidated balance sheet with the effective portion recorded in other comprehensive income and the ineffective portion recorded as a change in fair value of derivatives in the consolidated statement of operations. The contracts are effective and therefore the movement in other comprehensive income representing the effective portion for the six months ended June 30, 2023 was a loss of $4.3 million (June 30, 2022 — loss of $6.4 million). As the foreign exchange contracts settle, the realized gain or loss is reclassified from other comprehensive income into general, administration and corporate expenses of the consolidated statement of operations. For the six months ended June 30, 2023, the amount recognized within general, administration and corporate expenses for settled foreign exchange contracts was a realized loss of $3.7 million (June 30, 2022 — gain of $2.8 million). Embedded derivative on loss portfolio contract . The loss portfolio transfer contract includes a funds withheld arrangement that provides returns to the reinsurer based on Aspen’s investment performance, guaranteeing a minimum of 1.75% return. Such funds withheld arrangements are examples of embedded derivatives and therefore this instrument is accounted for as an option-based derivative. For the six months ended June 30, 2023, the amount recognized as a change in fair value of derivatives in the consolidated statement of operations is $8.3 million (June 30, 2022 — $Nil).

Deferred Policy Acquisition Cos

Deferred Policy Acquisition Costs	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs The following table represents a reconciliation of beginning and ending deferred acquisition costs for the twelve months ended December 31, 2022 and 2021: Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 ($ in millions) Balance at the beginning of the period $ 290.8 $ 306.6 Acquisition costs deferred 460.0 398.3 Amortization of deferred acquisition costs (431.8) (414.1) Balance at the end of the period $ 319.0 $ 290.8

Reserves for Losses and Adjustm

Reserves for Losses and Adjustment Expenses	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Reserves for Losses and Adjustment Expenses	Reserves for Losses and Loss Adjustment Expenses The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the twelve months ended December 31, 2022, 2021 and 2020: As at December 31, 2022 2021 2020 ($ in millions) Provision for losses and LAE at the start of the year $ 7,611.8 $ 7,165.3 $ 6,951.8 Less reinsurance recoverable (3,298.1) (3,195.2) (2,319.8) Net loss and LAE at the start of the year 4,313.7 3,970.1 4,632.0 Net loss and LAE expenses disposed (1) (1,840.1) — (818.5) Movement in net provision for losses and LAE for claims incurred: Current year 1,651.9 1,648.2 1,841.7 Prior years 28.1 45.1 (0.9) Total incurred 1,680.0 1,693.3 1,840.8 Net Losses and LAE payments for claims incurred: Current year (192.7) (729.1) (404.9) Prior years (1,098.4) (580.7) (1,359.7) Total paid (1,291.1) (1,309.8) (1,764.6) Foreign exchange (gains)/losses (49.3) (39.9) 80.4 Net losses and LAE reserves at the end of the year 2,813.2 4,313.7 3,970.1 Plus reinsurance recoverable on unpaid losses at the end of the year 4,897.7 3,298.1 3,195.2 Provision for losses and LAE at the end of the year $ 7,710.9 $ 7,611.8 $ 7,165.3 ________________ (1) Net loss and LAE expenses disposed of $1,840.1 million represent the net loss reserves as at May 20, 2022 (“Closing Date”) for losses in relation to 2019 and prior accident years, in addition to the $770.0 million of ceded reserves under the previous ADC agreement, recognizing a total recoverable of $2,610.1 million. These reserves were rolled forward from the initial effective date of September 30, 2021, at which time the net losses reserves were $3,120.0 million. As at December 31, 2022 the total amount recoverable from Enstar under the LPT was $2,132.0 million (As at December 31, 2021 recoverable from Enstar on the ADC was — $838.1 million) which includes claims paid and reserve development since the Closing Date. Net loss and LAE expenses disposed in 2020 includes the transfer of reserves under the ADC agreement providing $770.0 million of cover and the loss portfolio transfer transactions for our surety insurance book of $42.0 million and our U.S. accident and health book of $6.5 million. For the twelve months ended December 31, 2022, there was an increase of $28.1 million in the Company’s estimate of the ultimate claims to be paid in respect of prior accident years compared to an increase of $45.1 million for the twelve months ended December 31, 2021. Overall, prior year reserve strengthening totaled $28.1 million in 2022, compared with net unfavorable development of $45.1 million in 2021. Prior year reserve strengthening excludes the full economic benefit of the recoveries from the ADC of $58.3 million which is currently within reinsurance recoverables on unpaid losses. Reinsurance . Net reserve releases of $58.8 million in 2022 were mainly due to releases on prior year development on post-LPT years of $24.6 million and the favorable impact of the LPT of $34.2 million. Insurance . Net unfavorable reserve development of $86.9 million in 2022 included adverse prior year development on post-LPT years of $37.6 million and the unfavorable movement of $49.3 million due to the impact of the LPT, mainly reflecting the one-off costs in relation to the LPT recognized in 2022 and the change from ADC on a fixed allocation basis to the LPT. The following tables show an analysis of incurred claims and allocated loss adjustment expenses, net of reinsurance and cumulative paid claims and allocated claim adjustment expenses, net of reinsurance as at December 31, 2022, 2021, 2020, 2019 2018, 2017, 2016, 2015, 2014 and 2013. Under the LPT agreement, the Company has reinsured net losses incurred on all accident years 2019 and prior. This has resulted in total incurred claims, IBNR and loss adjustment expenses in the loss development triangles for 2019 and prior to be Nil. The loss development triangles are derived from all business written by the Company as although a limited number of contracts are written which have durations of greater than one year the contracts do not meet the definition of a long duration contract. All amounts included in the following tables related to transactions denominated in a foreign currency have been translated into U.S. Dollars using the exchange rates in effect at December 31, 2022. The Company has chosen to disaggregate the business in its Insurance segment, for the purposes of these loss development triangles as: Property; Casualty; Marine Aviation and Energy; and Financial and Professional insurance lines. The Company considers that this presentation of its Insurance lines loss development triangles more precisely reflects meaningful trending information. The Company presents its loss development triangles for the Reinsurance segment in line with the reportable reinsurance lines: Property Catastrophe and Other Property; Casualty; and Specialty. Property Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Accident For the Years Ended December 31, Cumulative Number of Reported Claims Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 126.7 114.4 114.2 109.9 110.9 109.0 109.3 109.5 102.1 106.1 — — 2014 162.6 154.9 132.4 133.0 132.2 130.7 130.1 125.2 131.1 — 9,949 2015 233.3 199.0 193.9 196.3 196.9 193.9 179.6 189.2 — 11,549 2016 233.9 245.0 240.0 241.3 242.5 233.4 244.8 — 10,773 2017 290.4 253.7 246.8 248.1 280.9 247.7 — 9,717 2018 196.3 198.1 182.2 196.2 177.3 — 8,308 2019 122.5 126.5 104.1 107.8 — 6,852 2020 199.9 195.9 205.1 24.4 7,542 2021 204.6 199.5 38.2 6,583 2022 163.9 62.9 4,171 Total $ 1,772.5 Property Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 37.5 73.7 86.8 98.6 103.0 105.8 107.6 107.9 106.8 106.1 2014 39.9 85.2 112.5 122.0 126.0 127.3 128.7 129.9 131.1 2015 56.3 138.3 165.1 174.1 190.1 188.9 190.4 189.2 2016 65.7 166.1 198.1 219.2 228.6 233.7 244.8 2017 95.0 185.0 217.2 237.9 242.1 247.7 2018 60.3 153.6 176.1 173.0 177.3 2019 48.0 88.6 99.3 107.8 2020 60.1 122.9 150.1 2021 58.2 118.6 2022 40.8 Total $ 1,513.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 259.0 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 259.0 Casualty Insurance Lines As at December 31, 2022 Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance Cumulative Number of Reported Claims Accident For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 128.6 112.8 111.6 116.8 99.8 101.1 101.4 100.0 107.8 86.7 — 3,392 2014 139.9 122.6 134.2 124.0 131.0 134.9 131.8 137.9 107.4 — 3,914 2015 197.9 217.9 180.5 197.5 230.1 228.3 250.4 197.2 — 4,775 2016 211.5 182.5 177.6 184.2 195.1 247.4 163.3 — 4,818 2017 176.3 169.9 173.4 190.5 234.6 154.4 — 5,495 2018 119.4 122.5 132.2 169.7 94.4 — 5,500 2019 122.0 144.4 155.3 88.3 — 5,198 2020 131.1 139.3 138.7 72.1 3,755 2021 170.5 185.6 119.7 3,356 2022 201.1 132.1 2,709 Total $ 1,417.1 Casualty Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 2.1 25.1 38.2 51.2 65.9 77.9 82.0 83.9 84.0 86.7 2014 2.5 12.6 31.5 57.3 70.1 93.1 105.4 104.0 107.4 2015 3.0 16.4 55.1 90.2 135.0 163.6 174.5 197.2 2016 4.0 22.0 38.6 79.7 106.1 128.8 163.3 2017 3.4 22.3 51.2 93.4 110.3 154.4 2018 3.0 27.2 41.4 65.5 94.4 2019 6.2 16.7 68.0 88.3 2020 — 9.2 36.1 2021 3.00 8.8 2022 23.2 Total $ 959.8 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 457.3 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 457.3 Marine, Aviation and Energy Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Cumulative Number of Reported Claims For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 319.4 332.1 340.7 324.3 331.5 345.0 343.6 338.7 346.5 319.7 — 4,179 2014 308.6 312.2 297.2 308.9 304.5 311.4 300.7 317.6 279.1 — 4,058 2015 295.3 297.0 279.3 283.7 307.2 309.9 327.3 302.7 — 4,076 2016 258.8 229.0 227.5 227.9 217.7 224.3 199.2 — 4,431 2017 209.3 199.9 206.2 213.7 231.5 205.3 — 6,059 2018 170.1 207.1 207.9 238.8 169.7 — 5,153 2019 145.5 152.8 151.1 124.0 — 3,662 2020 110.2 111.2 125.7 17.5 3,856 2021 93.0 96.1 18.3 4,863 2022 107.7 58.8 3,810 Total $ 1,929.2 Marine, Aviation and Energy Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 41.2 130.9 203.9 234.1 263.5 283.1 299.1 309.3 309.0 319.7 2014 53.2 116.0 188.1 208.6 231.3 249.5 261.7 274.2 279.1 2015 44.6 122.5 172.7 192.1 220.0 255.5 277.5 302.7 2016 30.8 81.9 141.3 163.1 189.5 197.3 199.2 2017 40.0 97.0 139.6 167.6 155.7 205.3 2018 26.7 104.3 132.6 154.7 169.7 2019 33.4 72.4 117.5 124.0 2020 28.5 66.4 88.6 2021 23.5 52.3 2022 24.9 Total $ 1,765.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 163.7 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 163.7 Financial and Professional Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 104.3 98.7 103.1 99.6 98.6 89.9 88.8 95.1 101.0 82.9 — 606 2014 133.2 128.8 127.4 117.7 128.9 118.0 118.8 124.3 118.9 — 794 2015 171.9 173.4 183.1 187.1 188.0 183.0 189.9 163.9 — 1,085 2016 188.4 209.3 213.7 199.7 182.9 189.0 163.2 — 1,244 2017 203.9 179.6 184.5 185.2 208.8 166.7 — 1,737 2018 153.7 169.4 151.2 163.2 125.4 — 4,643 2019 246.8 259.6 253.9 195.2 — 23,831 2020 346.3 346.2 336.2 118.0 105,947 2021 284.5 302.8 170.4 34,942 2022 314.8 265.2 3,487 Total $ 1,970.0 Financial and Professional Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 7.9 20.6 30.6 64.6 62.8 71.1 73.2 76.4 79.9 82.9 2014 2.8 30.2 52.7 71.1 78.5 84.0 90.9 102.3 118.9 2015 13.5 43.1 69.5 88.6 108.8 137.6 144.1 163.9 2016 14.8 70.7 100.7 128.7 124.6 133.8 163.2 2017 27.1 51.0 83.0 116.2 135.6 166.7 2018 17.4 71.6 97.8 113.3 125.4 2019 26.8 86.2 136.8 195.2 2020 47.2 120.8 174.2 2021 42.8 90.2 2022 17.5 Total $ 1,298.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 671.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 671.9 Property Catastrophe and Other Property Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 212.3 193.7 184.1 173.1 171.7 168.5 165.8 162.9 159.5 156.3 — 832 2014 185.8 172.6 157.1 145.7 145.9 141.1 141.2 140.1 138.1 — 900 2015 210.0 183.7 173.8 153.5 168.9 168.9 177.2 160.6 — 1,048 2016 264.2 264.6 263.2 242.1 237.7 230.1 229.8 — 1,307 2017 550.7 529.4 511.7 500.4 595.5 447.7 — 1,953 2018 323.5 362.8 356.0 571.0 304.5 — 1,780 2019 237.3 249.6 358.7 203.6 — 1,399 2020 317.5 402.1 348.9 81.0 1,379 2021 647.3 472.7 196.9 1,411 2022 392.3 266.7 950 Total $ 2,854.5 Property Catastrophe and Other Property Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 33.9 95.7 142.6 154.1 158.6 160.1 161.6 156.0 156.0 156.3 2014 36.9 98.5 124.4 133.7 137.4 136.0 137.6 137.8 138.1 2015 35.6 93.6 124.2 136.7 153.6 155.9 159.5 160.6 2016 55.8 160.5 200.9 211.6 224.4 230.7 229.8 2017 123.0 355.4 413.5 437.1 433.7 447.7 2018 122.1 290.1 296.8 315.3 304.5 2019 28.1 143.9 191.4 203.6 2020 41.8 165.5 237.3 2021 75.0 233.2 2022 65.5 Total $ 2,176.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 677.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 677.9 Casualty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 211.7 226.7 221.6 219.1 202.3 197.7 200.3 197.9 191.6 151.9 — 1,700 2014 201.8 204.0 212.3 205.5 199.0 202.1 198.0 191.1 144.7 — 1,843 2015 191.1 197.6 207.3 209.8 207.5 203.7 198.8 135.1 — 2,038 2016 229.3 241.4 241.0 251.0 258.5 258.5 174.6 — 2,153 2017 241.0 239.1 249.7 248.9 265.5 147.7 — 2,166 2018 226.0 255.0 262.5 264.3 130.4 — 2,002 2019 232.5 253.1 252.0 82.1 — 1,567 2020 252.6 233.6 197.9 123.2 1,088 2021 205.7 215.6 135.9 815 2022 248.7 179.1 478 Total $ 1,628.7 Casualty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 3.4 15.7 42.3 64.4 91.8 113.5 126.0 137.9 144.2 151.9 2014 2.5 13.6 37.4 59.6 85.4 105.9 123.4 133.0 144.7 2015 3.3 17.5 37.8 64.7 88.4 107.3 121.4 135.1 2016 8.9 32.9 62.9 94.8 124.6 145.3 174.6 2017 8.7 30.2 58.5 96.5 115.7 147.7 2018 7.1 33.2 73.0 103.8 130.4 2019 9.1 36.2 60.9 82.1 2020 9.1 27.6 44.1 2021 7.8 37.1 2022 9.4 Total $ 1,057.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 571.6 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 571.6 Specialty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 140.5 135.7 127.7 116.3 115.7 111.9 111.6 108.3 104.8 98.1 — 579 2014 149.5 137.5 129.5 120.8 123.6 122.2 118.0 116.6 105.4 — 622 2015 163.2 166.4 161.1 155.9 154.5 150.0 150.0 132.5 — 774 2016 235.8 236.6 234.6 227.6 222.6 218.8 197.6 — 938 2017 375.4 388.4 372.1 361.1 364.2 325.9 — 1,336 2018 392.7 391.9 390.3 419.5 342.1 — 1,403 2019 470.3 493.4 397.4 423.6 — 1,537 2020 412.8 600.0 374.1 53.1 1,470 2021 156.6 151.6 55.8 1,276 2022 193.9 107.9 969 Total $ 2,344.8 Specialty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 24.3 68.7 84.4 91.4 98.4 98.4 99.3 99.0 98.1 98.1 2014 16.2 55.2 79.8 87.8 98.0 100.9 102.5 104.4 105.4 2015 17.3 55.2 102.5 119.9 128.7 131.7 131.7 132.5 2016 58.2 149.5 163.9 181.7 191.8 201.8 197.6 2017 94.1 237.4 268.9 303.8 314.4 325.9 2018 26.7 279.0 312.2 328.5 342.1 2019 272.5 379.6 398.8 423.6 2020 212.8 269.6 290.4 2021 28.2 53.2 2022 25.8 Total $ 1,994.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 350.2 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 350.2 Reconciliation of Incurred and Paid Claims Development to total Provision for Losses and LAE Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 ($ in millions) Net outstanding liabilities: Insurance lines - Property insurance lines 259.0 289.3 - Casualty insurance lines 457.3 725.6 - Marine, aviation and energy insurance lines 163.7 427.9 - Financial and professional insurance lines 671.9 808.7 Total insurance lines 1,551.9 2,251.5 Reinsurance lines - Property catastrophe and other property reinsurance 677.9 784.9 - Casualty reinsurance 571.6 975.3 - Specialty reinsurance 350.2 472.3 Total reinsurance lines 1,599.7 2,232.5 Net loss and LAE 3,151.6 4,484.0 Reinsurance recoverable on unpaid losses: Insurance lines 2,907.8 2,117.4 Reinsurance lines 1,989.9 1,180.7 Total reinsurance recoverable on unpaid losses 4,897.7 3,298.1 Deferred gain on retroactive contracts 42.7 58.3 Unallocated claims incurred 41.4 56.6 Other reinsurance balances recoverable (1) (429.3) (286.4) Carbon syndicate reserves 5.2 1.0 Other 1.6 0.2 (338.4) (170.3) Provision for losses and LAE at the end of the year 7,710.9 7,611.8 ________________ (1) Other reinsurance balances recoverable primarily include short term recoverables to be collected. Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 Insurance 16.6 % 27.0 % 19.4 % 13.6 % 8.3 % 9.6 % 6.0 % 4.7 % 2.2 % 2.6 % Reinsurance 20.5 % 33.7 % 15.7 % 10.1 % 7.8 % 5.9 % 4.3 % 2.7 % 2.3 % 1.9 % Reserves for Losses and Loss Adjustment Expenses The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the six months at June 30, 2023 and June 30, 2022: As at June 30, As at June 30, 2023 2022 ($ in millions) Provision for losses and LAE at the start of the period $ 7,710.9 $ 7,611.8 Less reinsurance recoverable (4,897.7) (3,298.1) Net loss and LAE at the start of the period 2,813.2 4,313.7 Net loss and LAE expenses transferred (1) — (1,840.1) Movement in net provision for losses and LAE for claims incurred: Current year 723.5 775.0 Prior years (6.4) (7.3) Total incurred 717.1 767.7 Net Losses and LAE payments for claims incurred: Current year (30.8) (35.5) Prior years (438.6) (616.9) Total paid (469.4) (652.4) Foreign exchange losses/(gains) 22.0 (83.6) Net losses and LAE reserves at the end of the period 3,082.9 2,505.3 Plus reinsurance recoverable on unpaid losses at the end of the period 4,658.0 5,006.5 Provision for losses and LAE at the end of the period $ 7,740.9 $ 7,511.8 __________________ (1) Net loss and LAE expenses transferred of $1,840.1 million relates to the LPT with Enstar and represents the net loss reserves as at May 20, 2022 (“Closing Date”) for losses in relation to 2019 and prior accident years, in addition to the $770.0 million of ceded reserves under the previous ADC agreement, recognizing a total recoverable of $2,610.1 million. These reserves were rolled forward from the initial effective date of September 30, 2021, at which time the net losses reserves were $3,120.0 million. As at June 30, 2023 the total amount recoverable from Enstar under the LPT was $1,877.3 million (As at December 31, 2022 — $2,132.0 million) which includes claims paid and reserve development since the Closing Date. For the six months ended June 30, 2023, there was a reduction of $6.4 million in the Company’s estimate of the ultimate claims to be paid in respect of prior accident years compared to a reduction of $7.3 million for the six months ended June 30, 2022. Reinsurance . Net unfavorable reserve development of $2.1 million in the six months ended June 30, 2023 were mainly due to reserve strengthening in property catastrophe and reinsurance lines of business, offset by reserve releases from casualty reinsurance and specialty reinsurance. Insurance . Net reserve releases of $8.5 million in the six months ended June 30, 2023 included favorable development of $13.2 million representing the movement on the deferred gain on the LPT, offset by unfavorable development on post-LPT years of $4.7 million.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Aspen Holdings and Aspen Bermuda are incorporated under the laws of Bermuda. Under Bermuda law, the corporate tax rate is zero and, as a result, Aspen Holdings and Aspen Bermuda are not taxed on any Bermudian income or capital gains. In the event of any Bermudian income or capital gains taxes being imposed, Aspen Holdings and Aspen Bermuda have received an assurance from the Bermuda Minister of Finance that such entities will be exempt from those taxes until March 31, 2035. The Company’s U.S. operating companies were subject to a U.S. federal income tax rate of 21%. The Company’s U.K. operating companies were taxed at the U.K. corporate tax rate of 19%. Total income tax (benefit)/expense for the twelve months ended December 31, 2022, 2021 and 2020 was allocated as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Income tax (benefit)/expense allocated to net income $ (78.1) $ 5.3 $ 18.4 Income tax (benefit)/expense allocated to other comprehensive income (23.9) 0.3 0.5 Total income tax (benefit)/expense $ (102.0) $ 5.6 $ 18.9 (Loss)/income from operations before income taxes and income tax expense/(benefit) attributable to that (loss)/income for the twelve months ended December 31, 2022, 2021 and 2020 is provided in the tables below: Twelve Months Ended December 31, 2022 (Loss)/income Current tax Deferred tax Total income tax ($ in millions) Bermuda $ (103.3) $ — $ — $ — U.S. (1) (2) 34.8 14.8 (102.9) (88.1) U.K. (3) 62.4 7.0 — 7.0 Other (4) (20.9) 4.7 (1.7) 3.0 Total $ (27.0) $ 26.5 $ (104.6) $ (78.1) Twelve Months Ended December 31, 2021 Income/(loss) Current tax Deferred tax Total income tax ($ in millions) Bermuda $ 22.9 $ — $ — $ — U.S. 5.0 5.8 — 5.8 U.K. 75.1 — (0.3) (0.3) Other (67.9) 2.7 (2.9) (0.2) Total $ 35.1 $ 8.5 $ (3.2) $ 5.3 Twelve Months Ended December 31, 2020 (Loss)/income Current tax Deferred tax Total income tax ($ in millions) Bermuda $ (81.5) $ — $ — $ — U.S 19.7 8.9 — 8.9 U.K. 11.0 0.1 — 0.1 Other 12.8 10.3 (0.9) 9.4 Total $ (38.0) $ 19.3 $ (0.9) $ 18.4 ________________ (1) The U.S. current tax expense of $14.8 million includes $2.3 million of Base Erosion and Anti-abuse Tax (2021— $5.8 million), of which $1.1 million relates to the U.S. operating subsidiaries and $1.2 million to Aspen UK’s U.S. branch. (2) The U.S. deferred tax benefit of $102.9 million is mainly due to a change in judgment about the realizability of the deferred tax asset in the U.S. operating subsidiaries. The decrease in valuation allowance relating to our U.S. operations is driven by a change in judgment about the recoverability of deferred tax assets in the U.S. operating subsidiaries. We have concluded that the deferred tax assets of our U.S. operating subsidiaries will more likely than not be fully utilized over time, and therefore the previously recognized valuation allowance in relation to U.S. operating subsidiaries has been reversed. (3) The U.K. current tax expense of $7.0 million results from an intraperiod tax allocation. (4) Current tax expense and deferred tax (benefit) in “Other” mostly relates to the Swiss branches of Aspen UK and withholding taxes payable in Australia. As noted above, the tax rate in Bermuda, the Company’s country of domicile, is zero. Application of the statutory income tax rate for operations in other jurisdictions produces a differential to the expected income tax (benefit)/expense as shown in the table below. The reconciliation between the income tax (benefit)/expense and the amount that would result from applying the statutory rate for the Company for the twelve months ended December 31, 2022, 2021 and 2020 is provided in the table below: Twelve Months Ended December 31, 2022 2021 2020 Income Tax Reconciliation ($ in millions) Income tax benefit at statutory tax rate of zero percent $ — $ — $ — Overseas statutory tax rates differential 16.8 (0.9) (3.8) Base erosion and anti-abuse tax (BEAT) expense 2.3 6.1 4.3 Prior year adjustments (1) (2.9) 0.5 (25.0) Change in valuation allowance (2) (98.9) 9.6 40.8 Impact of unrecognized tax benefits (3) — — — Australian non-resident withholding tax 1.5 0.6 1.0 Foreign exchange (0.3) (1.5) 0.2 Non-deductible expenses 2.4 2.4 4.7 Impact of changes in statutory tax rates (4) (5.7) (11.5) (3.8) Tax effect of OCI in income statement 6.7 — — Total income tax (benefit)/expense $ (78.1) $ 5.3 $ 18.4 ________________ (1) The submission dates for filing income tax returns for the Company’s U.S. and U.K. operating subsidiaries are after the submission date of this report. Accordingly, the final tax liabilities may differ from the estimated income tax expense included in this report and may result in prior year adjustments being reported. The prior period adjustments for the twelve months ended December 31, 2022 predominantly relate to the determination of the results of the branches of the U.K. operating subsidiaries. The prior period adjustments for the twelve months ended December 31, 2021 and 2020 predominantly relate to the determination of results in the U.K. (2) The 2022 valuation allowance movement includes nil relating to U.K deferred tax assets in U.K. operating subsidiaries, $4.8 million decrease relating to deferred tax assets in the branches of the U.K. and Bermuda operating subsidiaries, and $94.1 million decrease from U.S. operations. The decrease in valuation allowance relating to our U.S. operations is driven by a change in judgment about the recoverability of deferred tax assets in the U.S. operating subsidiaries. We have concluded that the deferred tax assets of our U.S. operating subsidiaries will more likely than not be fully utilized over time, and therefore the previously recognized valuation allowance in relation to U.S. operating subsidiaries has been reversed. (3) In 2022, the Company did not have any unrecognized tax benefits. Income tax returns that have been filed by the Company’s U.S. Operating Subsidiaries are subject to examination for 2019 and later tax years. The Company’s U.K. operating subsidiaries’ income tax returns are potentially subject to examination for 2021 and later tax years as these periods are considered “open” by the U.K. Tax Authority. The Company accrues interest and penalties related to an underpayment of income taxes, if applicable, as income tax expenses. The Company does not believe it will be subject to any penalties in any open tax years and has not accrued any such amounts for the twelve months ended December 31, 2022. (4) The U.K. tax rate has changed from April 1, 2023 from 19% to 25%. The tax effects of temporary differences and carryforwards that give rise to deferred tax assets and deferred tax liabilities are presented in the following table as at December 31, 2022 and 2021: As at December 31, 2022 2021 ($ in millions) Deferred tax assets: Operating loss carryforwards 167.6 170.2 Capital loss carryforwards 6.7 0.3 Insurance reserves: Losses and loss adjustment expenses 28.3 16.7 Unrealized losses on investments 20.6 — Accrued expenses 6.1 4.6 Foreign tax credit carryforwards 19.8 20.2 Insurance reserves: Unearned premiums 36.0 28.3 Intangible assets 0.7 — Office properties and equipment 14.2 15.1 Operating lease liabilities 18.5 19.2 Other temporary differences 3.7 2.9 Total deferred tax assets 322.2 277.5 Less valuation allowance (145.7) (225.9) Deferred tax assets, net of valuation allowance $ 176.5 $ 51.6 Deferred tax liabilities: Investments — (2.5) Intangible assets — (2.8) Deferred acquisition costs (37.0) (28.6) Right-of-use operating lease assets (13.7) (10.6) Insurance reserves: Losses and loss adjustment expenses (0.2) (8.3) Other temporary differences (6.4) (1.6) Total deferred tax (liabilities) (57.3) (54.4) Net deferred tax assets/(liabilities) $ 119.2 $ (2.8) Deferred tax liabilities and assets represent the tax effect of carryforwards and temporary differences between the value of assets and liabilities for financial statement purposes and such values as measured by U.K., U.S. and other tax laws and regulations. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences and carry forwards become deductible or creditable. Management considers the scheduled reversal of existing taxable temporary differences, carryback availability, projected future taxable income, and tax-planning strategies in making this assessment. As at December 31, 2022, the Company has net operating losses carryforwards for U.S. federal income tax purposes of $376.5 million (2021 — $443.1 million), of which $309.4 million relates to the U.S. operating subsidiaries and $67.1 million to Aspen UK’s U.S. branch. The Company also has net operating losses carryforwards for U.K. corporate tax purposes of $280.5 million (2021 — $168.9 million), deferred syndicate profits of $19.9 million (2021 — $66.2 million losses), and losses in other jurisdictions of $118.8 million (2021 — $103.9 million). The $376.5 million that are available to offset future U.S. federal taxable income will expire between 2032 and 2041. The amount of pre-merger net operating losses carryforwards that can be used each year is limited by section 382 to $6.5 million per year for Aspen UK’s U.S. branch, and $39.2 million in 2023, $23.1 million in 2024, and $20.8 million per year for the 15 years thereafter for the U.S. operating subsidiaries. The net operating losses in the U.K. and other jurisdictions are available to offset future corporate income in those jurisdictions over an indefinite period. For U.S. federal income tax purposes, the Company has capital loss carryforwards of $31.7 million, of which $15.0 million relates to the U.S. operating subsidiaries and $16.7 million to Aspen UK’s branch, expiring between 2026 and 2027 and nil charitable contribution carryforwards (2021 — $0.1 million). For U.K. corporate tax purposes, the Company has foreign tax credit carryforwards of $19.8 million (2021 — $20.2 million) which are available to offset future U.K. corporate tax arising on the same foreign source of income over an indefinite period. A valuation allowance of $18.0 million (2021 — $119.7 million) on U.S. deferred tax assets (which includes these loss carryforwards) has been recognized at December 31, 2022 relating to Aspen UK’s U.S. branch. The valuation allowance relating to the deferred tax assets of the U.S. operating companies has been reversed as a result of a change in judgment over the likelihood that a tax benefit will be realized. A valuation allowance of $106.7 million (2021 — $88.7 million) has been established against U.K. deferred tax assets.

Capital Structure

Capital Structure	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Capital Structure	Capital Structure The following table provides a summary of the Company’s authorized and issued share capital as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2021 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2021 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 ________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. (a) Ordinary Shares Issued Ordinary Shares. The Company’s issued ordinary shares of par value $0.01 at both December 31, 2022 and 2021 was 60,395,839. The Company did not acquire any ordinary shares for the twelve months ended December 31, 2022. (b) Preference Shares Preference Shares Issuance. On May 2, 2013, the Company issued 11,000,000 5.950% Fixed-to-Floating Rate Perpetual Non-Cumulative Preference Shares, with a liquidation preference of $25 per share (the “5.950% Preference Shares”). Net proceeds were $270.6 million, consisting of $275.0 million of total liquidation preference less $4.4 million of issuance expenses. The 5.950% Preference Shares are listed on the NYSE under symbol “AHLPRC”. On September 20, 2016, the Company issued 10,000,000 shares of 5.625% Perpetual Non-Cumulative Preference Shares (the “5.625% Preference Shares”). The 5.625% Preference Shares have a liquidation preference of $25 per share. Net proceeds were $241.3 million, consisting of $250.0 million of total liquidation preference less $8.7 million of issuance expenses. The 5.625% Preference Shares are listed on the NYSE under the symbol “AHL PRD”. On August 13, 2019, the Company issued 10,000,000 depositary shares, each of which represents 1/1000 th interest in a share of the newly designated 5.625% Perpetual Non-Cumulative Preference Shares. The depositary shares have a liquidation preference of $25 per share. Net proceeds were $241.6 million, comprising $250.0 million of total liquidation preference less $8.4 million of issuance expenses. The depositary shares are listed on the NYSE under the symbol “AHL PRE”. (c) Additional Paid-in Capital Additional paid-in capital as at December 31, 2022 was $1,514.7 million (December 31, 2021 — $1,514.7 million). Included within additional paid-in capital is the aggregate liquidation preferences of the Company’s preference shares of $775.0 million less issue costs of $21.5 million (December 31, 2021 — $775.0 million less issue costs of $21.5 million). Capital Structure The following table provides a summary of the Company’s authorized and issued share capital as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2022 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2022 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 __________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. (a) Ordinary Shares Issued Ordinary Shares . The Company’s issued ordinary shares of par value $0.01 at both June 30, 2023 and December 31, 2022 was 60,395,839. The Company did not acquire any ordinary shares for the six months ended June 30, 2023. (b) Preference Shares Preference Shares Issuance . On May 2, 2013, the Company issued 11,000,000 5.950% Fixed-to-Floating Rate Perpetual Non-Cumulative Preference Shares, with a liquidation preference of $25 per share (the “5.950% Preference Shares”). Net proceeds were $270.6 million, consisting of $275.0 million of total liquidation preference less $4.4 million of issuance expenses. The first floating rate-period commenced on July 1, 2023 (payable on October 1, 2023), where the floating rate was tied to LIBOR, being 3-month LIBOR, and as contemplated by the governing instrument, 3-month LIBOR was the rate for 3-month deposits in U.S. dollars on June 29, 2023. The 5.950% Preference Shares are listed on the NYSE under symbol “AHLPRC”. On September 20, 2016, the Company issued 10,000,000 shares of 5.625% Perpetual Non-Cumulative Preference Shares (the “5.625% Preference Shares”). The 5.625% Preference Shares have a liquidation preference of $25 per share. Net proceeds were $241.3 million, consisting of $250.0 million of total liquidation preference less $8.7 million of issuance expenses. The 5.625% Preference Shares are listed on the NYSE under the symbol “AHL PRD”. On August 13, 2019, the Company issued 10,000,000 depositary shares, each of which represents 1/1000 th interest in a share of the newly designated 5.625% Perpetual Non-Cumulative Preference Shares. The depositary shares have a liquidation preference of $25 per share. Net proceeds were $241.6 million, comprising $250.0 million of total liquidation preference less $8.4 million of issuance expenses. The depositary shares are listed on the NYSE under the symbol “AHL PRE”.

Dividends

Dividends	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Dividends	Dividends Dividends. On March 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 April 1, 2023 March 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 April 1, 2023 March 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 April 1, 2023 March 15, 2023 ________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share. In the twelve months ended December 31, 2022, the Company paid an ordinary shares dividend of $40 million to Highlands Bermuda Holdco, Ltd., the holder of all the Company’s ordinary shares. The Company also paid an ordinary shares dividend of $20 million to Highlands Bermuda Holdco, Ltd. on April 3, 2023. Dividends Dividends . On June 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 July 1, 2023 June 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 July 1, 2023 June 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 July 1, 2023 June 15, 2023 __________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000 th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share.

Retirement Plans

Retirement Plans	6 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans The Company operates defined contribution retirement plans for the majority of its employees at varying rates of their salaries. Total contributions by the Company to the retirement plans were $12.5 million in the twelve months ended December 31, 2022 (2021 — $13.5 million, 2020 — $12.1 million).

Share-Based Payments and Long-T

Share-Based Payments and Long-Term Incentive Plan	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Share Based Payments and Long-term Incentive Plan	Share-Based Payments and Long-Term Incentive Plan In 2019, the Company implemented a new long-term incentive scheme, under which annual awards are split equally between Performance Units and Exit Units. Performance units vesting conditions have been amended in the current year and vest after two years subject to the Company achieving certain thresholds of operating income over a two year period. Exit Units vest upon change of control (sale or IPO) and achieving predetermined multiplies of invested capital return targets. Both Performance Units and Exit Units are cash-based awards.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	6 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Intangible Assets and Goodwill The following table provides a summary of the Company’s intangible assets for the twelve months ended December 31, 2022 and 2021: Twelve Months Ended December 31, 2022 Beginning of the Year Additions/(Disposals) Amortization Impairment End of the Year ($ in millions) Intangible Assets Trademarks $ 1.3 $ — $ (0.1) $ — $ 1.2 Insurance Licenses 16.7 — — — 16.7 Goodwill 3.9 — — — 3.9 Total $ 21.9 $ — $ (0.1) $ — $ 21.8 Twelve Months Ended December 31, 2021 Beginning of the Year Additions/(Disposals) Amortization Impairment End of the Year ($ in millions) Intangible Assets Trademarks $ 1.6 $ — $ (0.3) $ — $ 1.3 Agency Relationships 0.6 — (0.6) — — Insurance Licenses 16.7 — — — 16.7 Goodwill 3.9 — — — 3.9 Total $ 22.8 $ — $ (0.9) $ — $ 21.9 Aspen’s intangible assets relate to trademarks, contracts to sell products through independent broker and agents (Agency Relationships), an agreement for renewal rights with Liberty Specialty Markets Limited, non-compete agreements and licenses to trade in the U.S. and U.K. In 2010, the Company acquired licenses with a value of $10.0 million. The total value of the licenses as at December 31, 2022 was $16.7 million. This includes $4.5 million of acquired licenses held by Aspen Specialty and $2.1 million of acquired licenses held by Aspen UK. The insurance licenses are considered to have an indefinite life and are not being amortized. In addition, Aspen has recognized goodwill of $2.1 million on the acquisition of equity voting interest of Blue Waters, a specialist marine insurance agency in October 2016 and of $1.8 million on the purchase in January 2017 of 49% share of Digital Re, a digital risk and specialty insurer.

Operating Leases (Notes)

Operating Leases (Notes)	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Lessee, Operating Leases	Operating Leases As at December 31, 2022, the Company has recognized right-of-use operating lease assets of $72.8 million, net of impairment and operating lease liabilities of $95.5 million. Right-of-use operating lease assets comprise primarily of leased office real estate globally and other assets. For all office real estate leases, rent incentives, including reduced-rent and rent-free periods and contractually agreed rent increases during the lease term, have been included when determining the present value of future cash flows. As part of the Company’s operating effectiveness and efficiency program, the Company has consolidated its office space. Where negotiations are either in advanced stages of discussion and it is probable that the sub-lease transactions will be completed, or the Company has agreed terms to sub-lease our office space, the Company has assessed the right-of-use lease assets for impairment and have recognized a $6.7 million credit (2021 — $0.4 million) charge within the period. The Company believes its office space is sufficient to conduct its operations for the foreseeable future in these locations. The Company has no lease transactions between related parties. Operating lease charge. The following table summarizes the operating lease charge for the twelve months ended December 31, 2022 and 2021: For the Twelve Months Ended December 31, 2022 December 31, 2021 ($ in millions) Amortization charge on right-of-use operating leased assets $ 10.1 $ 12.0 Interest on operating lease liabilities 5.4 5.5 Operating lease charge $ 15.5 $ 17.5 Lease Liabilities. The following table summarizes the maturity of lease liabilities under non-cancellable leases as of December 31, 2022 and 2021: December 31, 2022 December 31, 2021 ($ in millions) Operating leases — maturities 2022 $ — $ 17.0 2023 15.4 17.0 2024 15.2 16.5 2025 14.9 16.1 2026 14.1 15.3 2027 12.6 13.8 Later years 47.2 48.0 Total minimum lease payments $ 119.4 $ 143.7 Less imputed interest (23.9) (28.5) Total lease liabilities $ 95.5 $ 115.2 Other lease information. The following table summarizes the cash flows on operating leases for the twelve months ended December 31, 2022 and 2021, and other supplemental information: For the Twelve Months Ended December 31, 2022 December 31, 2021 ($ in millions) Cash paid for amounts included in the measurement of lease liabilities - Operating cash outflow from operating leases $ (15.5) $ (17.5) Right-of-use assets obtained in exchange for lease obligations - Operating leases $ 1.9 $ 23.9 Reduction to Right-of-use assets resulting from reductions to lease obligations - Operating leases $ 7.0 $ 2.3 Weighted Averages - Operating leases, remaining lease terms (years) 8.1 8.8 - Operating leases, average discount rate 5.0 % 5.0 %

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Apollo’s indirect subsidiary, Apollo Asset Management Europe PC LLP (“AAME”), serves as the investment manager for the Company and certain of the Company’s subsidiaries, and Apollo’s indirect subsidiary, Apollo Management Holdings, L.P. (“AMH”), provides the Company with management consulting services and advisory services. Additionally, certain employees of Apollo and its affiliates serve on the Board. A description of relationships and transactions that have existed or that the Company and certain of the Company’s subsidiaries has entered into with Apollo and its affiliates are described below. Investment Management Relationships AAME provides centralized asset management investment advisory and risk services for the portfolio of the Company’s investments and investments of such subsidiaries pursuant to the investment management agreements (“IMAs”) that have been entered into with AAME. In addition, pursuant to the IMAs, AAME may engage sub-advisors or delegates to provide certain of the investment advisory and management services to the Company’s subsidiaries. Such sub-advisors may include affiliates of AAME. Under each of the IMAs, AAME will be paid an annual investment management fee (the “Management Fee”) which will be based on a cost-plus structure. The “cost” is comprised of the direct and indirect fees, costs, expenses and other liabilities arising in or otherwise connected with the services provided under the IMAs. The “plus” component will be a mark-up in an amount of up to 25% determined based on an applicable transfer pricing study. The Management Fee will be subject to certain maximum threshold levels, including an annual fee cap of 15 bps of the total amount of investable assets. Affiliated sub-advisors, including AMI and AMC, will also earn additional fees for sub-advisory services rendered. During the year ended December 31, 2022, the Company recognized IMA fees of $4.9 million (2021 — $5.8 million; 2020 — $5.3 million), of which $4.5 million (2021 — $3.2 million) remains payable to AAME at year end. Management Consulting Agreement As previously disclosed, the Company entered into a Management Consulting Agreement, dated March 28, 2019 (the “Management Consulting Agreement”), with AMH. Pursuant to the Management Consulting Agreement, AMH will provide the Company management consulting and advisory services related to the business and affairs of the Company and its subsidiaries. The Company will pay AMH in consideration for its services under the Management Consulting Agreement, an annual management consulting fee equal to the greater of (i) 1% of the consolidated net income of the Company and its subsidiaries for the applicable fiscal year, or (ii) $5 million. During the year ended December 31, 2022, the Company recognized Management Consulting fees of $5.0 million (2021 — $5.0 million; 2020 — $5.0 million), of which $1.3 million remains payable to AMH at year end (2021 — $Nil). Related Party Investments During the year, the Company bought or held the following securities or investments in Apollo: Apollo Real Estate Fund. As at December 31, 2022, the Company’s investment in Apollo Real Estate Fund had a fair value of $25.3 million. This investment is included in other investments on the consolidated balance sheet. Income earned on this investment was $1.6 million and is included in net investment income on the consolidated statement of operations and other comprehensive income. Apollo Origination Partnership (“AOP”) Fund. As at December 31, 2022, the Company’s investment in the AOP Fund had a fair value of $12.7 million. This investment is included in other investments on the consolidated balance sheet. The Company incurred gains of $1.5 million and is included in net investments income on the consolidated statement of operations and other comprehensive income. AOP Class A notes; AOP Class B notes. As at December 31, 2022, the Company’s investment in AOP Class A notes had a fair value of $30.0 million. As at December 31, 2022, the Company’s investment in AOP Class B notes had a fair value of $14.8 million. The Company incurred losses of $0.2 million and $0.2 million on AOP Class A and B notes, respectively, and is included in realized and unrealized investment losses on the consolidated statement of operations and other comprehensive income. These investments are included in privately-held investments on the consolidated balance sheet. In 2022 there were no expenses incurred relating to any of these investments. The above transactions were entered into at arm’s length. Other Payables to Related Parties Related Party Transactions Apollo’s indirect subsidiary, Apollo Asset Management Europe PC LLP (“AAME”), serves as the investment manager for the Company and certain of the Company’s subsidiaries, and Apollo’s indirect subsidiary, Apollo Management Holdings, L.P. (“AMH”), provides the Company with management consulting services and advisory services. Additionally, certain employees of Apollo and its affiliates serve on the Board. A description of relationships and transactions that have existed or that the Company and certain of the Company’s subsidiaries has entered into with Apollo and its affiliates are described below. Investment Management Relationships AAME provides centralized asset management investment advisory and risk services for the portfolio of the Company’s investments and investments of such subsidiaries pursuant to the investment management agreements (“IMAs”) that have been entered into with AAME. In addition, pursuant to the IMAs, AAME may engage sub-advisors or delegates to provide certain of the investment advisory and management services to the Company’s subsidiaries. Such sub-advisors may include affiliates of AAME. Under each of the IMAs, AAME will be paid an annual investment management fee (the “Management Fee”) which will be based on a cost-plus structure up to 25% based on an applicable transfer pricing study. The Management Fee will be subject to certain maximum threshold levels, including an annual fee cap of 15 bps of the total amount of investable assets. Affiliated sub-advisors, including AMI and AMC, will also earn additional fees for sub-advisory services rendered. During the six months ended June 30, 2023, the Company recognized IMA fees of $5.2 million (June 30, 2022 — $0.6 million), of which $2.4 million (December 31, 2022 — $4.5 million) remains payable to AAME as at June 30, 2023. Management Consulting Agreement As previously disclosed, the Company entered into a Management Consulting Agreement, dated March 28, 2019 (the “Management Consulting Agreement”), with AMH. Pursuant to the Management Consulting Agreement, AMH will provide the Company management consulting and advisory services related to the business and affairs of the Company and its subsidiaries. The Company will pay AMH in consideration for its services under the Management Consulting Agreement, an annual management consulting fee equal to the greater of (i) 1% of the consolidated net income of the Company and its subsidiaries for the applicable fiscal year, or (ii) $5 million. During the six months ended June 30, 2023, the Company recognized Management Consulting fees of $2.5 million (June 30, 2022 — $2.5 million), of which $2.5 million remains payable to AMH as at June 30, 2023 (December 31, 2022 — $1.3 million). Related Party Investments During the six months ended June 30, 2023, the Company bought or held the following securities or investments in Apollo originated and managed investments: Apollo U.S. Real Estate Fund II LP. As at June 30, 2023, the Company’s investment in Apollo U.S. Real Estate Fund II LP had a fair value of $22.9 million (December 31, 2022 — $25.3 million). This investment is included in other investments on the consolidated balance sheet. The Company incurred losses of $1.3 million (June 30, 2022 — $Nil) and is included in net investment income on the consolidated statement of operations and other comprehensive income. Apollo Origination Partnership (“AOP”) Fund. As at June 30, 2023, the Company’s investment in the AOP Fund had a fair value of $12.6 million (December 31, 2022 —$12.7 million). This investment is included in other investments on the consolidated balance sheet. The Company incurred losses of $0.4 million (June 30, 2022 — $0.2 million) and is included in net investments income on the consolidated statement of operations and other comprehensive income. AOP Class A notes; AOP Class B notes. As at June 30, 2023, the Company’s investment in AOP Class A notes had a fair value of $28.6 million (December 31, 2022 —$30.0 million). As at June 30, 2023, the Company’s investment in AOP Class B notes had a fair value of $14.0 million (December 31, 2022 —$14.8 million). The Company earned income of $1.3 million (June 30, 2022 — $0.5 million) and $0.7 million (June 30, 2022 — $0.3 million) on AOP Class A and B notes, respectively, and is included in realized and unrealized investment losses on the consolidated statement of operations and other comprehensive income. These investments are included in privately-held investments on the consolidated balance sheet. During the six months ended June 30, 2023, there were no expenses incurred relating to any of these investments (June 30, 2022 — $Nil). The above transactions were entered into at arm’s length. Other Payables to Related Parties As at June 30, 2023, the Company had an intercompany payable balance of $2.2 million (December 31, 2022 — $2.0 million), due to its parent, Highlands Bermuda Holdco, Ltd.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingent Liabilities (a) Restricted assets The Company’s subsidiaries are obliged by the terms of its contractual obligations to U.S. policyholders and by obligations to certain regulatory authorities to facilitate issue of letters of credit or maintain certain balances in trust funds for the benefit of policyholders. The following table details the forms and value of Company’s material restricted assets as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 707.1 $ 891.3 Third party 2,817.7 3,099.7 Letters of credit / guarantees (1) 471.3 539.8 Total restricted assets (excluding illiquid assets) 3,996.1 4,530.8 Other investments — illiquid assets 221.3 151.3 Total restricted assets and illiquid assets $ 4,217.4 $ 4,682.1 Total as percent of cash and invested assets (2) 59.4 % 59.7 % ________________ (1) As at December 31, 2022, the Company had pledged funds of $471.3 million (December 31, 2021 — $539.8 million) as collateral for the secured letters of credit. (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. Real Estate Funds. We invest in real estate funds which, as is typical for this type of investment, have lock-up periods. A lock-up period is the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. As at December 31, 2022, the lock-up periods across these funds range from one quarter to several years. Thereafter these funds could also be redeemed on a pro-rata basis depending on the liquidity position of the fund. There are no assurances as to when the Company may be able to withdraw, in whole or in part, its redemption request from the fund. Other Investments - Equity Method. On December 23, 2019, the Company committed $5.0 million as an equity investment in the holding company of a multi-line reinsurer. The strategy for the multi-line reinsurer is to combine a diversified reinsurance business, focused primarily on long-tailed lines of property and casualty business and, potentially to a lesser extent, life business, with a diversified investment strategy. During the period ending December 31, 2022, $1.6 million (December 31, 2021 — $2.5 million) capital was invested in multi-line reinsurer. The Company’s current arrangements with our bankers for the issue of letters of credit require us to provide collateral in the form of cash and investments for the full amount of all secured and undrawn letters of credit that are outstanding. We monitor the proportion of our otherwise liquid assets that are committed to trust funds or to the collateralization of letters of credit. As at December 31, 2022 and 2021, these funds amounted to approximately 59.4% of the $7.1 billion and approximately 59.7% of the $7.8 billion of investable assets held by the Company, respectively. We do not consider that this unduly restricts our liquidity at this time. For more information on our credit facilities and long-term debt arrangements, refer to Note 23, “Credit Facility and Short-term Debt” of these consolidated financial statements. Funds at Lloyd’s. AUL operates at Lloyd’s as the corporate member for Syndicate 4711. AUL also participates in underwriting activities of Carbon Syndicate 4747. Lloyd’s determines required regulatory capital by considering the underwriting activities that AUL participates in. Such capital, called Funds at Lloyd’s, consists of investable assets as at December 31, 2022 in the amount of $489.5 million (2021 — $565.8 million). The amounts provided as Funds at Lloyd’s will be drawn upon and become a liability of the Company in the event of Syndicate 4711 declaring a loss at a level that cannot be funded from other resources, or if Syndicate 4711 requires funds to cover a short-term liquidity gap. The amount which the Company provides as Funds at Lloyd’s is not available for distribution to the Company for the payment of dividends. Aspen Managing Agency Limited, the managing agent to Syndicate 4711, is also required by Lloyd’s to maintain a minimum level of capital which as at December 31, 2022 was £0.4 million (December 31, 2021 — £0.4 million). This is not available for distribution by the Company for the payment of dividends. U.S. Reinsurance Trust Fund. For its U.S. reinsurance activities, Aspen UK has established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen UK’s U.S. reinsurance liabilities, which were $1,166.4 million as at December 31, 2022 and $1,470.5 million as at December 31, 2021. As at December 31, 2022, the balance (including applicable letter of credit facilities) held in the trust was $1,389.5 million (2021 — $1,581.9 million). Aspen Bermuda has also established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen Bermuda’s liabilities to its U.S. cedants which was $380.3 million and $450.4 million as at December 31, 2022 and 2021, respectively. As at December 31, 2022, the balance held in the U.S. trust fund and other Aspen Bermuda trusts was $509.2 million (2021 — $519.7 million). U.S. Surplus Lines Trust Fund. Aspen UK and Syndicate 4711 have also established a U.S. surplus lines trust fund with a U.S. bank to secure liabilities under U.S. surplus lines policies. The balance held in trust as at December 31, 2022 was $215.1 million (2021 — $216.0 million). U.S. Regulatory Deposits. As at December 31, 2022, Aspen Specialty had a total of $6.7 million (2021 — $6.9 million) on deposit with six U.S. states in order to satisfy state regulations for writing business in those states. AAIC had a further $6.5 million (2021 — $6.4 million) on deposit with twelve U.S. states. Canadian Trust Fund. Aspen UK has established a Canadian trust fund with a Canadian bank to secure a Canadian insurance license. As at December 31, 2022, the balance held in trust was CAD$185.8 million ($137.2 million) (2021 — CAD$196.8 million). Australian Trust Fund. Aspen UK has established an Australian trust fund with an Australian bank to secure policyholder liabilities and as a condition for maintaining an Australian insurance license. As at December 31, 2022, the balance held in trust was AUD$183.9 million ($124.7 million) (2021 — AUD$226.6 million). Swiss Trust Fund. Aspen UK has established a Swiss trust fund with a Swiss bank to secure policyholder liabilities and as a condition for maintaining a Swiss insurance license. As at December 31, 2022, the balance held in trust was CHF9.4 million ($10.2 million) (2021 — CHF8.0 million). Singapore Fund. Aspen UK has established a segregated Singaporean bank account to secure policyholder liabilities and as a condition for maintaining a Singaporean insurance license and meet local solvency requirements. As at December 31, 2022, the balance in the account was SGD$174.7 million ($130.3 million) (2021 — SGD$178.0 million). (b) Contingent liabilities In common with the rest of the insurance and reinsurance industry, the Company is also subject to litigation and arbitration in the ordinary course of business. The Company’s Operating Subsidiaries are regularly engaged in the investigation, conduct and defense of disputes, or potential disputes, resulting from questions of insurance or reinsurance coverage or claims activities. Pursuant to insurance and reinsurance arrangements, many of these disputes are resolved by arbitration or other forms of alternative dispute resolution. Such legal proceedings are considered in connection with estimating the Company’s Insurance Reserves — Loss and Loss Adjustment Expenses, as provided on the Company’s consolidated balance sheet. In some jurisdictions, noticeably the U.S., a failure to deal with such disputes or potential disputes in an appropriate manner could result in an award of “bad faith” punitive damages against the Company’s Operating Subsidiaries. In accordance with ASC 450-20-50-4b, for (a) reasonably possible losses for which no accrual is made because any of the conditions for accrual in ASC 450-20-25-2 are not met and (b) reasonably possible losses in excess of the amounts accrued pursuant to ASC 450-20-30-1, the Company will provide an estimate of the possible loss or range of possible loss or state that such an estimate cannot be made. As at December 31, 2022, it was the opinion of the Company’s management based on available information that the probability of the ultimate resolution of pending or threatened litigation or arbitrations having a material effect on the Company’s financial condition, results of operations or liquidity would be remote. Commitments and Contingent Liabilities (a) Restricted assets The Company’s subsidiaries are obliged by the terms of its contractual obligations to U.S. policyholders and by obligations to certain regulatory authorities to facilitate issue of letters of credit or maintain certain balances in trust funds for the benefit of policyholders. The following table details the forms and value of Company’s material restricted assets as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 617.0 $ 707.1 Third party 2,773.8 2,817.7 Letters of credit / guarantees (1) 266.5 471.3 Total restricted assets (excluding illiquid assets) 3,657.3 3,996.1 Other investments — illiquid assets 213.4 221.3 Total restricted assets and illiquid assets $ 3,870.7 $ 4,217.4 Total as percent of cash and investable assets (2) 52.6 % 59.4 % __________________ (1) As at June 30, 2023, the Company had pledged funds as collateral for the secured letters of credit of $266.5 million (December 31, 2022 — $471.3 million). (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. The Company’s banking arrangements related to letters of credit, require the Company to provide collateral in the form of cash and securities for the full amount of all secured and undrawn letters of credit that are outstanding. The Company monitors the proportion of liquid assets that are committed to trust funds or to the collateralization of letters of credit. As at June 30, 2023 and December 31, 2022, these funds amounted to approximately 52.6% of the $7.4 billion and approximately 59.4% of the $7.1 billion of investable assets held by the Company, respectively. We do not consider that this unduly restricts our liquidity at this time. Real Estate Funds. The Company invests in real estate funds which have lock-up periods, being the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. As at June 30, 2023, the lock-up periods across these funds range from one quarter to several years. Thereafter these funds may be redeemed on a pro-rata basis depending on the liquidity position of the fund. There are no assurances as to when the Company may receive, in whole or in part, its redemption request from the fund. Funds at Lloyd’s. AUL operates at Lloyd’s as the corporate member for Syndicate 4711. AUL also participates in underwriting activities of Carbon Syndicate 4747. Lloyd’s determines required regulatory capital by considering the underwriting activities of AUL, called Funds at Lloyd’s and consists of investable assets as at June 30, 2023 in the amount of $551.0 million (December 31, 2022 — $489.5 million). The Funds at Lloyd’s will be drawn upon and become a liability of the Company in the event of Syndicate 4711 declaring a loss at a level that cannot be funded from other resources, or if Syndicate 4711 requires funds to cover a short-term liquidity gap. The amount which the Company provides as Funds at Lloyd’s is not available for distribution to the Company for the payment of dividends. Aspen Managing Agency Limited, the managing agent to Syndicate 4711, is also required by Lloyd’s to maintain a minimum level of capital which as at June 30, 2023 was £0.4 million (December 31, 2022 — £0.4 million). This is not available for distribution by the Company for the payment of dividends. U.S. Reinsurance Trust Fund. For its U.S. reinsurance activities, Aspen UK has established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen UK’s U.S. reinsurance liabilities, which were $1,009.3 million as at June 30, 2023 and $1,166.4 million as at December 31, 2022. As at June 30, 2023, the balance (including applicable letter of credit facilities) held in the trust was $1,167.8 million (December 31, 2022 — $1,389.5 million). Aspen Bermuda has also established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen Bermuda’s liabilities to its U.S. cedants which was $306.7 million and $380.3 million as at June 30, 2023 and December 31, 2022, respectively. As at June 30, 2023, the balance held in the U.S. trust fund and other Aspen Bermuda trusts was $383.2 million (December 31, 2022 — $509.2 million). U.S. Surplus Lines Trust Fund. Aspen UK and Syndicate 4711 have also established a U.S. surplus lines trust fund with a U.S. bank to secure liabilities under U.S. surplus lines policies. The balance held in trust as at June 30, 2023 was $141.0 million (December 31, 2022 — $215.1 million). U.S. Regulatory Deposits. As at June 30, 2023, Aspen Specialty had a total of $10.3 million (December 31, 2022 — $6.7 million) on deposit with six U.S. states in order to satisfy state regulations for writing business in those states. AAIC had a further $6.7 million (December 31, 2022 — $6.5 million) on deposit with twelve U.S. states. Canadian Trust Fund. Aspen UK has established a Canadian trust fund with a Canadian bank to secure a Canadian insurance license. As at June 30, 2023, the balance held in trust was CAD$200.9 million ($151.8 million) (December 31, 2022 — CAD$185.8 million). Australian Trust Fund. Aspen UK has established an Australian trust fund with an Australian bank to secure policyholder liabilities and as a condition for maintaining an Australian insurance license. As at June 30, 2023, the balance held in trust was AUD$153.2 million ($102.0 million) (December 31, 2022 — AUD$183.9 million). Swiss Trust Fund. Aspen UK has established a Swiss trust fund with a Swiss bank to secure policyholder liabilities and as a condition for maintaining a Swiss insurance license. As at June 30, 2023, the balance held in trust was CHF$9.5 million ($10.6 million) (December 31, 2022 — CHF9.4 million). Singapore Fund. Aspen UK has established a segregated Singaporean bank account to secure policyholder liabilities and as a condition for maintaining a Singaporean insurance license and meet local solvency requirements. As at June 30, 2023, the balance in the account was SGD$172.6 million ($127.5 million) (December 31, 2022 — SGD$174.7 million). (b) Contingent liabilities In common with the rest of the insurance and reinsurance industry, the Company is also subject to litigation and arbitration in the ordinary course of business. The Company’s Operating Subsidiaries are regularly engaged in the investigation, conduct and defense of disputes, or potential disputes, resulting from questions of insurance or reinsurance coverage or claims activities. Pursuant to insurance and reinsurance arrangements, many of these disputes are resolved by arbitration or other forms of alternative dispute resolution. Such legal proceedings are considered in connection with estimating the Company’s Insurance Reserves — Loss and Loss Adjustment Expenses, as provided on the Company’s consolidated balance sheet. In some jurisdictions, noticeably the U.S., a failure to deal with such disputes or potential disputes in an appropriate manner could result in an award of “bad faith” punitive damages against the Company’s Operating Subsidiaries. In accordance with ASC 450-20-50-4b, for (a) reasonably possible losses for which no accrual is made because any of the conditions for accrual in ASC 450-20-25-2 are not met and (b) reasonably possible losses in excess of the amounts accrued pursuant to ASC 450-20-30-1, the Company will provide an estimate of the possible loss or range of possible loss or state that such an estimate cannot be made. As at June 30, 2023, it was the opinion of the Company’s management based on available information that the probability of the ultimate resolution of pending or threatened litigation or arbitrations having a material effect on the Company’s financial condition, results of operations or liquidity would be remote.

Concentration of Credit Risk

Concentration of Credit Risk	6 Months Ended
	Jun. 30, 2023
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	Concentrations of Credit Risk The Company is potentially exposed to concentrations of credit risk in respect of amounts recoverable from reinsurers, investments and cash and cash equivalents, and insurance and reinsurance balances owed by the brokers with whom the Company transacts business. The Company defines credit risk tolerances in line with the risk appetite set by our Board and they, together with the Group’s risk management function, monitor exposures to individual counterparties. Any exceptions are reported to senior management and the Risk Committee of the Board of Directors. Reinsurance recoverables The total amount recoverable by the Company from reinsurers as at December 31, 2022 was $4,897.7 million (2021 — $3,298.1 million) of which $2,092.4 million was uncollateralized (2021 — $1,981.4 million). As at December 31, 2022, of the Company’s uncollateralized reinsurance recoverables 9.7% (2021 — 10.8%) were with Munich Re which is rated A+ by A.M. Best and AA- by S&P, 16.3% (2021 —15.9% ) were with Everest Re which is rated A+ by A.M Best and A+ by S&P, and 8.2% (2021 — 9.3%) were with Lloyd’s which is rated A by A.M. Best and A+ by S&P. These are the Company’s largest exposures to individual reinsurers. On June 16, 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses (Topic 326) ” which introduced a new impairment model, known as the current expected loss model (“CECL”), which is based on expected losses rather than incurred losses. Under the new credit loss model, the Company would recognize an allowance for its estimate of expected credit losses and this would apply to reinsurance receivables. Following the adoption of this ASU with effect from January 1, 2020, the Company recognized a reduction in the Company’s reinsurance recoverables by $3.7 million as at December 31, 2022 (2021 — $3.3 million). For the twelve months ended December 31, 2022 there was an increase in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2021 — $0.5 million decrease). Underwriting premium receivables The total underwriting premium receivable by the Company as at December 31, 2022 was $1,482.4 million (2021 — $1,304.6 million). As at December 31, 2022, $18.3 million of the total underwriting premium receivable balance has been due for settlement for more than one year. The Company assesses the recoverability of premium receivables through a review of policies and the concentration of receivables by broker. Allowance for credit losses of $25.0 million as at December 31, 2022 (2021 — $30.2 million) for underwriting premiums unlikely to be collected. Investments and cash and cash equivalents The Company’s investment policies include specific provisions that limit the allowable holdings of a single issue and issuer. As at December 31, 2022, there were no investments in any single issuer, other than the U.S. government and the Canadian government in excess of 2% of the aggregate investment portfolio. Business through brokers The Company underwrites a significant amount of its business through brokers and a credit risk exists should any of these brokers be unable to fulfill their contractual obligations in respect of insurance or reinsurance balances due to the Company. The following table shows the largest brokers that the Company transacted business within the three years ended December 31, 2022 and the proportion of gross written premiums from each of those brokers. Twelve Months Ended December 31, 2022 2021 2020 (in percentages) Aon Corporation 22.3 % 17.3 % 15.8 % Marsh & McLennan Companies, Inc. 21.8 17.5 15.4 Willis Group Holdings, Ltd. 8.0 9.6 10.4 Other brokers/non-broker sources (1) 47.9 55.6 58.4 Total 100.0 % 100.0 % 100.0 % Gross written premiums ($ millions) $ 4,338.7 $ 3,938.4 $ 3,698.5 __________________ (1) No other individual broker accounted for more than 10% of total gross written premiums. Concentrations of Credit Risk The Company is potentially exposed to concentrations of credit risk in respect of amounts recoverable from reinsurers, investments and cash and cash equivalents, and insurance and reinsurance balances owed by the brokers with whom the Company transacts business. The Company defines credit risk tolerances in line with the risk appetite set by our Board and they, together with the Group’s risk management function, monitor exposures to individual counterparties. Any exceptions are reported to senior management and the Risk Committee of the Board of Directors. Reinsurance recoverables At June 30, 2023, the total amount recoverable by the Company from reinsurers was $4,658.0 million (December 31, 2022 — $4,897.7 million). Of the Company’s reinsurance recoverable balance at June 30, 2023, 56.0% is collateralized by our reinsurers, 43.5% is recoverable from reinsurers rated A- or higher by major rating agencies and 0.5% is recoverable from reinsurers rated lower than A- by major rating agencies (December 31, 2022 — 57.9%, 42.0% and 0.1%, respectively). As at June 30, 2023, the Company’s largest collateralized exposures to individual reinsurers represent 16.0% (December 31, 2022 —16.3%), 9.2% (December 31, 2022 — 9.7%), and 7.8% (December 31, 2022 — 8.2%). Under the current expected credit loss model (“CECL”), the Company recognized a provision against reinsurance recoverables of $3.3 million as at June 30, 2023 (December 31, 2022 — $3.7 million). For the six months ended June 30, 2023 there was a decrease in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2022 — $0.4 million increase). Underwriting premium receivables The total underwriting premium receivable by the Company as at June 30, 2023 was $1,676.8 million (December 31, 2022 — $1,482.4 million). As at June 30, 2023, $5.9 million of the total underwriting premium receivable balance has been due for settlement for more than one year. The Company assesses the recoverability of premium receivables through a review of policies and the concentration of receivables by broker. Allowance for credit losses of $21.6 million as at June 30, 2023 (December 31, 2022 — $25.0 million) for underwriting premiums unlikely to be collected. Investments and cash and cash equivalents The Company’s investment policies include specific provisions that limit the allowable holdings of a single issue and issuer. As at June 30, 2023, there were no investments in any single issuer, other than the U.S. government and the Canadian government in excess of 2% of the aggregate investment portfolio.

Reclassifications from Accumula

Reclassifications from Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Reclassifications from Accumulated Other Comprehensive Income	Reclassifications from Accumulated Other Comprehensive Income The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the twelve months ended December 31, 2022 and 2021: Amount Reclassified from AOCI Details about the AOCI Components Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Affected Line Item in the ($ in millions) Available for sale: Realized (gains) on sale of securities and cash and cash equivalents $ (3.9) $ (24.8) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 58.9 4.4 Realized and unrealized investment losses 55.0 (20.4) Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 55.0 $ (20.4) Net income/(loss) Realized derivatives: Net realized gains on settled derivatives 15.4 (6.2) General, administrative and corporate expenses Tax on settled derivatives — — Income tax (expense)/benefit $ 15.4 $ (6.2) Net income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 70.4 $ (26.6) Net income/(loss) Reclassifications from Accumulated Other Comprehensive Income The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the six months ended June 30, 2023 and 2022: Amount Reclassified from AOCI Details about the AOCI Components Six Months Ended June 30, 2023 Six Months Ended June 30, 2022 Affected Line Item in the ($ in millions) Available for sale: Realized gains on sale of securities and cash and cash equivalents $ (0.4) $ (2.3) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 7.2 30.1 Realized and unrealized investment losses 6.8 27.8 Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 6.8 $ 27.8 Net income/(loss) Realized derivatives: Net realized loss on settled derivatives (4.3) (6.4) General, administrative and corporate expenses Tax on settled derivatives — 0.6 Income tax (expense)/benefit $ (4.3) $ (5.8) Net Income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 2.5 $ 22.0 Net income/(loss)

Credit Facilities and Short-ter

Credit Facilities and Short-term Debt	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Credit Facilities and Short-term Debt	Credit Facilities and Short-term Debt In the normal course of its operations, the Company enters into agreements with financial institutions to obtain financing through secured and unsecured credit facilities. Credit Agreement. On December 1, 2021, Aspen Holdings and certain of its direct or indirect subsidiaries (collectively, the “Borrowers”) entered into a Third Amended and Restated Credit Agreement, as further amended from time to time (the “Credit Agreement”) with various lenders and Barclays Bank plc, as administrative agent, which amends and restates the Amended and Restated Credit Agreement, dated as of June 12, 2013 and the Second Amended and Restated Credit Agreement, dated as of March 27, 2017, among Aspen Holdings, certain subsidiaries thereof, various lenders and Barclays Bank plc, as administrative agent. The Credit Agreement will be used by the Borrowers to finance the working capital needs of the Aspen Holdings and its subsidiaries, for letters of credit in connection with the insurance and reinsurance businesses of the Company and its subsidiaries and borrowings for other general corporate purposes. Initial availability under the Credit Agreement is $300,000,000 and the Company has the right to request (subject to the terms and conditions of the Credit Agreement) an increase to the credit facility by up to $100,000,000. The Credit Agreement will expire on December 1, 2026. As at December 31, 2022, there were no borrowings outstanding under the Credit Agreement. The fees and interest rates on the loans and the fees on the letters of credit payable by the Borrowers under the Credit Agreement are based upon the credit ratings for the Company’s long-term unsecured senior, non-credit enhanced debt rating of the Company, as determined by S&P and Moody’s. In addition, the fees for a letter of credit vary based upon whether the applicable Borrower has provided collateral (in the form of cash or qualifying debt securities) to secure its reimbursement obligations with respect to such letter of credit. Under the Credit Agreement, the Company must not permit (a) consolidated tangible net worth as at the last day of each fiscal quarter of the Company to be less than the sum of (i) $2,019,600,000, (ii) 25% of consolidated net income during the period from January 1, 2021 to and including such last day of such fiscal quarter (if positive) and (iii) 25% of the aggregate net cash proceeds of all issuances by the Company of shares of its capital stock during the period from January 1, 2021 to and including such last day of such fiscal quarter, but excluding (x) any amount included in the Company’s accumulated other comprehensive income or loss related to unrealized gains or losses on available for sale securities and (y) during the period from January 1, 2022, any amount included in net unrealized investment gains or losses, related to unrealized gains or losses on trading securities, (b) the ratio of its total consolidated debt to the sum of such debt plus our consolidated tangible net worth to exceed 35% as at the last day of any fiscal quarter of the Company or (c) any material insurance subsidiary to have a financial strength rating of less than “B++” from A.M. Best. The Credit Agreement contains other customary affirmative and negative covenants, including (subject to various exceptions) restrictions on the ability of the Company and its subsidiaries to incur indebtedness, create or permit liens on their assets, engage in mergers or consolidations, dispose of assets, pay dividends or other distributions, purchase or redeem the Company’s equity securities, make investments and enter into transactions with affiliates. In addition, the Credit Agreement has customary events of default, including (subject to certain materiality thresholds and grace periods) payment default, failure to comply with covenants, material inaccuracy of representation or warranty, bankruptcy or insolvency proceedings, change of control and cross-default to other debt agreements. Other Credit Facilities. (i) On March 2, 2023, Aspen Bermuda and Citibank Europe plc (“Citi Europe”) amended the committed letter of credit facility, dated July 30, 2012, as amended with effect on June 30, 2014, June 30, 2016, June 30, 2018, September 20, 2019, June 26, 2020 and June 29, 2022 (the “LOC Facility”). The June 29, 2022 amendment to the LOC Facility extends the term to June 30, 2024. The maximum aggregate amount available under the LOC Facility is $400.0 million. Under the LOC Facility, Aspen Bermuda will pay to Citi Europe (a) a letter of credit fee based on the available amounts of each letter of credit and (b) a commitment fee, which varies based upon usage, on the unutilized portion of the LOC Facility. Aspen Bermuda will also pay interest on the amount drawn by any beneficiary under the LOC Facility at a certain specific rate from the date of drawing until the date of reimbursement by Aspen Bermuda. In addition, Aspen Bermuda and Citi Europe entered into an uncommitted letter of credit facility whereby Aspen Bermuda has the ability to request letters of credit under this facility subject to the prior approval of Citi Europe. The fee associated with the uncommitted facility is a letter of credit fee based on the available amounts of each letter of credit issued under the uncommitted facility. Both the LOC Facility and the uncommitted facility are used to secure obligations of Aspen Bermuda to its policyholders. In addition to these facilities, we also use regulatory trusts to secure our obligations to policyholders. The terms of a pledge agreement between Aspen Bermuda and Citi Europe (pursuant to an assignment agreement dated October 11, 2006) dated January 17, 2006, as amended, were also amended on December 18, 2014 to change the types of securities or other assets that are acceptable as collateral under the LOC Facility and again on June 29, 2022 to change the representations and warranties granted by Aspen Bermuda in relation to the collateral provided under the LOC Facility. All other agreements relating to Aspen Bermuda’s LOC Facility, which now apply to the LOC Facility with Citi Europe, as previously filed with the SEC, remain in full force and effect. As at December 31, 2022, we had $416.8 million of outstanding collateralized letters of credit under the LOC Facility (December 31, 2021 — $452.4 million). (ii) On February 7, 2019, Aspen European and Aspen Holdings (acting as guarantor of Aspen European) entered into a letter of credit facility for the purpose of obtaining a letter of credit in favor of Aspen UK for a sum not to exceed $100 million to provide approved regulatory capital for Aspen UK. A letter of credit was issued in favor of Aspen UK for a sum of $100 million. This facility was amended and restated with respect to February 7, 2023, pursuant to which the $100 million letter of credit was extended to February 11, 2027. (iii) On October 27, 2022, AUL and Aspen Holdings (acting as guarantor of AUL), effected an amendment to a letter of credit facility agreement for the account of AUL, pursuant to which a syndicate of lenders issued a several letter of credit in an aggregate amount of $285,000,000, for the benefit of Lloyd’s, to support AUL’s Funds at Lloyd’s requirements in connection with the 2023 year of account at Lloyd’s. This further amended the letter of credit facility agreement, dated November 3, 2020, entered into between AUL, Aspen Holdings (acting as guarantor of AUL) and various lenders, for the account of AUL, pursuant to which a lender provided a maximum aggregate amount of $235,000,000, to support AUL’s Funds at Lloyd’s requirements in connection with the 2021 year of account at Lloyd’s, as amended on May 7, 2021, November 1, 2021 and May 6, 2022, in connection with the 2021 and 2022 underwriting years of account at Lloyd’s, as applicable. (iv) On December 1, 2022, AUL and Aspen Holdings (acting as guarantor of AUL) amended a Funds at Lloyd’s Facility Agreement dated November 25, 2020, as amended on December 2, 2021, for the account of AUL. This facility provides that a maximum aggregate amount of up to $80.0 million of acceptable securities may be deposited with, and for the benefit of, Lloyd’s on behalf of AUL to support AUL’s Funds at Lloyd’s requirements in connection with the 2023 year of account at Lloyd’s. (v) On December 1, 2022, AUL and Aspen Bermuda (acting as AUL’s guarantor) amended and restated a Funds a Lloyd’s Facility Agreement dated November 30, 2020, as amended on November 30, 2021, for the account of AUL. This facility provides that a maximum aggregate amount of up to $150 million of acceptable securities may be deposited with, and for the benefit of, Lloyd’s on behalf of AUL to support AUL’s Funds at Lloyd’s requirements in connection with the 2023 year of account at Lloyd’s. (vi) On November 5, 2021, Aspen Bermuda entered into an uncommitted Continuing Agreement for Standby Letters of Credit and Demand Guarantees, as amended on April 1, 2022, where Aspen Bermuda has the ability to request letters of credit to be used in support of policyholder obligations with the consent of the lender. The fee associated with this facility is a facility fee based on the aggregate face amount of outstanding letters of credit. As at December 31, 2022 we had $120 million of outstanding collateralized letters of credit under this facility. (vii) On April 1, 2021, the Company’s subsidiaries, AAIC and Aspen Specialty, each established a secured line of credit at Federal Home Loan Bank of Boston (“FHLBB”). Advances may be used to support general corporate purposes. The maximum amount available under these facilities will vary based on the borrower’s net admitted assets or reserve assets (total invested assets) and the lender’s underwriting criteria. Aspen Specialty’s maximum borrowing capacity available from FHLBB upon initial application is 15% of net admitted assets or approximately $223 million, and is subject to North Dakota approval. Under Texas state insurance law, without the prior consent of the Texas Department of Insurance, the amount of assets AAIC may pledge to secure debt obligations is limited to 10% of its reserve assets, resulting in a maximum borrowing capacity for AAIC under its FHLBB facility of approximately $141 million. Neither AAIC nor Aspen Specialty expects to draw on these facilities in the near future. (viii) On November 5, 2021, Aspen Holdings entered into a letter of credit facility agreement. The letter of credit issued under this facility is the for the benefit of Aspen Bermuda, as beneficiary, and has been applied towards the eligible capital of Aspen Bermuda, and classified as ancillary Tier 3 capital of such entity, in accordance with applicable Bermuda laws and regulations. The total commitment under the facility is $100,000,000. A letter of credit in the full amount of the available commitment has been issued to Aspen Holdings under this facility. (ix) On December 29, 2021, Aspen Holdings entered into a committed letter of credit facility agreement. The letter of credit issued under this facility is for the benefit of Aspen Bermuda, as beneficiary, and has been applied towards the eligible capital of Aspen Bermuda, and classified as ancillary Tier 3 capital of such entity, in accordance with applicable Bermuda laws and regulations. The total commitment under the facility is $75,000,000. A letter of credit in the full amount of the available commitment has been issued to Aspen Holdings under this facility. (x) On June 17, 2022, AUL and Aspen Holdings (acting as AUL’s guarantor) entered into a securities lending transaction, pursuant to a global master securities lending agreement. This facility provides that a maximum aggregate amount of up to $50 million of eligible securities may be loaned to AUL, for the benefit of, Lloyd’s, on behalf of AUL to support AUL’s Funds at Lloyd’s requirements in connection with the 2023 year of account at Lloyd’s. As at December 31, 2022, the market value of the loaned securities under this facility was approximately $50,000,000. (xi) On December 21, 2022, Aspen Bermuda entered into an uncommitted Continuing Letter of Credit Agreement (For Standby Letters of Credit), where Aspen Bermuda has the ability to request letters of credit to be used in support of policyholder collateral obligations with the consent of the lender. The fee associated with this facility is a facility fee based on the aggregate face amount of outstanding letters of credit. As at December 31, 2022, we had $100 million of outstanding collateralized letters of credit under this facility. (xii) On November 13, 2002, Aspen UK entered into an uncommitted secured letter of credit facility agreement, where Aspen UK has the ability to issue letters of credit to be used in support of policyholder collateral obligations with the consent of the lender. The fee associated with this facility is a facility fee based on the aggregate face amount of outstanding letters of credit. As at December 31, 2022, we had $75.1 million of outstanding collateralized letters of credit under this facility. (xiii) On January 27, 2021, Aspen UK entered into an uncommitted unsecured letter of credit facility agreement, where Aspen UK has the ability to issue letters of credit to be used in support of policyholder and internal reinsurance collateral obligations with the consent of the lender. The fee associated with this facility is a facility fee based on the aggregate face amount of outstanding letters of credit. As at December 31, 2022, we had $22.8 million of outstanding collateralized letters of credit under this facility. The above credit facilities include certain restrictive covenants customary for facilities of this type, including restrictions on indebtedness, consolidated tangible net worth, and minimum financial strength ratings, with such financial covenants largely consistent with these set forth in the Credit Agreement. In addition, the agreements include default covenants, which could require the Company to fully secure the outstanding amounts thereunder and/or result in the Company not being allowed to issue any new letters of credit. On November 13, 2013, the Company closed its offering of $300.0 million 4.65% Senior Notes due November 15, 2023 (the “2023 Senior Notes”). The net proceeds from the 2023 Senior Notes offering, before offering expenses, were $299.7 million and a portion of the proceeds was used to redeem the then outstanding 2014 Senior Notes. Subject to applicable law, the 2023 Senior Notes will be the senior unsecured obligations of Aspen Holdings and will rank equally in right of payment with all of our other senior unsecured indebtedness from time to time outstanding. In light of the impending maturity of the 2023 Senior Notes, the Company continues to monitor the capital markets. Subject to certain exceptions, so long as any of the senior notes described above remain outstanding, the Company has agreed that neither the Company nor any of its subsidiaries will (i) create a lien on any shares of capital stock of any designated subsidiary (currently Aspen UK and Aspen Bermuda, as defined in the Indenture), or (ii) issue, sell, assign, transfer or otherwise dispose of any shares of capital stock of any designated subsidiary. Certain events will constitute an event of default under the Indenture, including default in payment at maturity of any of our other indebtedness in excess of $50.0 million. The following table summarizes our contractual obligations under short-term debt as at December 31, 2022. Payments Due By Period Contractual Basis Less than 1 year Total ($ in millions) Short-term Debt Obligations $ 300.0 $ 300.0 The Senior Notes obligation disclosed above does not include the $14.3 million annual interest payable associated with the Senior Notes.

Credit Losses

Credit Losses	6 Months Ended
	Jun. 30, 2023
Credit Loss [Abstract]
Allowance for Expected Credit Losses	Allowance for Expected Credit Losses The following tables summarize the Company’s allowance for expected credit losses for the twelve months ended December 31, 2022 in investments, reinsurance recoverables and receivables following the adoption of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326) ”: Twelve Months Ended December 31, 2022 ($ in millions) Investments Reinsurance Recoverables Receivables Total Opening value as at January 1, 2022 $ 2.7 $ 3.3 $ 30.2 $ 36.2 Movement of the allowance for credit losses during the year 5.0 0.4 (5.2) 0.2 Closing value as at December 31, 2022 $ 7.7 $ 3.7 $ 25.0 $ 36.4 Twelve Months Ended December 31, 2021 ($ in millions) Investments Reinsurance Recoverables Receivables Total Opening value as at January 1, 2021 $ 0.2 $ 3.8 $ 34.0 $ 38.0 Movement of the allowance for credit losses during the year 2.5 (0.5) (3.8) (1.8) Closing value as at December 31, 2021 $ 2.7 $ 3.3 $ 30.2 $ 36.2

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company declared and paid an ordinary shares dividend of $20 million to Highlands Bermuda Holdco, Ltd., the holder of all the Company’s ordinary shares, on April 3, 2023. Subsequent Events In July 2023, we entered into a delayed draw term loan facility for $300 million, which remains undrawn.

Schedule I - Investments

Schedule I - Investments	12 Months Ended
	Dec. 31, 2022
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I - Investments	SCHEDULE I - INVESTMENTS For the Twelve Months Ended December 31, 2022, 2021 and 2020

Schedule II - Condensed Financi

Schedule II - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2022
Condensed Financial Information Disclosure [Abstract]
Schedule II - Condensed Financial Information of Registrant	SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT BALANCE SHEETS As at December 31, 2022 and 2021 As at December 31, 2022 As at December 31, 2021 ($ in millions, except per share amounts) ASSETS Fixed income maturities (trading) 40.5 42.6 Cash and cash equivalents 44.4 45.0 Investments in subsidiaries (1) 2,767.9 3,142.0 Intercompany funds due from affiliates 1.7 1.3 Right-of-use operating lease assets 2.0 2.5 Other assets 5.9 8.0 Total assets $ 2,862.4 $ 3,241.4 LIABILITIES Accrued expenses and other payables 22.3 25.5 Intercompany funds due to affiliates 180.5 139.0 Short-term debt 299.9 — Long-term debt — 299.9 Operating lease liabilities 1.7 2.2 Total liabilities $ 504.4 $ 466.6 SHAREHOLDERS’ EQUITY Ordinary Shares: 60,395,839 shares of par value $0.01 each (December 31, 2021 — 60,395,839) $ 0.6 $ 0.6 Additional paid in capital 1,514.7 1,514.7 Retained earnings 1,349.0 1,382.5 Accumulated other comprehensive income, net of taxes: Unrealized (loss)/gains on investments (333.2) 34.6 Gain/(loss) on derivatives 13.8 (1.6) Cumulative (losses) on foreign currency translation adjustments (186.9) (156.0) Total accumulated other comprehensive (loss) (506.3) (123.0) Total shareholders’ equity 2,358.0 2,774.8 Total liabilities and shareholders’ equity $ 2,862.4 $ 3,241.4 _________________ (1) The Company’s investment in subsidiaries is accounted for under the equity method and adjustments to the carrying value of these investments are made based on the Company’s share of capital, including share of income and expenses. Changes in the value were recognized in realized and unrealized investment gains and losses in the statement of operations. Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Twelve Months Ended December 31, 2020 ($ in millions) Operating Activities: Equity in net earnings/(losses) of subsidiaries and other investments, equity method $ 14.2 $ (90.5) $ (108.4) Dividend income 121.7 193.0 141.5 Net realized and unrealized investment (losses)/gains (4.0) (0.5) 2.5 Other income 1.0 — — Total revenues 132.9 102.0 35.6 Expenses: General, administrative and corporate expenses (62.7) (54.6) (74.6) Interest expense (14.3) (14.3) (14.3) Other expense (4.8) (3.3) (3.1) Income/(loss) from operations before income taxes 51.1 29.8 (56.4) Income tax expense — — — Net income /(loss) 51.1 29.8 (56.4) Amount attributable to non-controlling interest — — — Net income/(loss) attributable to Aspen Insurance Holdings Limited ordinary shareholders 51.1 29.8 (56.4) Other comprehensive (loss)/income, net of taxes: Change in unrealized (losses)/gains on investments (367.8) (158.6) 108.0 Net change from current period hedged transactions 15.4 (6.2) 0.3 Change in foreign currency translation adjustment (30.9) 21.4 (11.9) Other comprehensive (loss)/income, net of tax (383.3) (143.4) 96.4 Comprehensive (Loss) / Income $ (332.2) $ (113.6) $ 40.0 Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Twelve Months Ended December 31, 2020 ($ in millions) Cash Flows From Operating Activities: Net income (excluding equity in net earnings of subsidiaries) $ 36.9 $ 120.3 $ 52.0 Adjustments: Realized and unrealized losses/(gains) 19.7 (6.7) 1.5 (Gain)/loss on derivative contracts (15.4) 6.2 (0.3) Amortization of right-of-use operating lease assets 0.5 0.5 0.4 Interest on operating lease liabilities 0.1 0.1 (0.4) Change in other assets 2.1 (1.6) 0.5 Change in accrued expenses and other payables (3.2) 1.4 15.9 Change in intercompany activities 41.1 35.0 41.6 Change in right-of use assets — (2.0) — Change in operating lease liabilities (0.6) 1.5 — Net cash generated by operating activities 81.2 154.7 111.2 Cash Flows From/(Used in) Investing Activities: (Purchases)/proceeds of fixed income securities (10.0) (42.6) 75.6 Proceeds from sales and maturities of fixed maturities, trading 7.8 — — Investment in subsidiaries 5.0 (115.0) (87.3) Net cash from/(used in) investing activities 2.8 (157.6) (11.7) Cash Flows (Used in) Financing Activities: Net cash (used in) financing activities (84.6) (44.5) (44.5) (Decrease)/increase in cash and cash equivalents (0.6) (47.4) 55.0 Cash and cash equivalents — beginning of period 45.0 92.4 37.4 Cash and cash equivalents — end of period $ 44.4 $ 45.0 $ 92.4

Schedule III - Supplementary In

Schedule III - Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2022
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Schedule III - Supplementary Insurance Information	SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION For the Twelve Months Ended December 31, 2022, 2021 and 2020 Supplementary Information ($ in millions) Year Ended December 31, 2022 Deferred Policy Acquisition Costs Net Reserves for Losses and LAE Net Net Premiums Earned Net Investment Income Losses and LAE Expenses Policy Acquisition Expenses Net Premium Written General and Administrative Expenses Reinsurance $ 227.2 $ 1,360.7 $ 862.4 $ 1,251.8 $ 770.3 $ 252.4 $ 1,426.4 $ 142.5 Insurance 91.8 1,452.5 857.8 1,436.9 909.7 179.4 1,469.6 244.0 Total $ 319.0 $ 2,813.2 $ 1,720.2 $ 2,688.7 $ 188.1 $ 1,680.0 $ 431.8 $ 2,896.0 $ 386.5 Year to date December 31, 2021 Deferred Policy Acquisition Costs Net Reserves for Losses and LAE Net Net Net Investment Income Losses and LAE Expenses Policy Acquisition Expenses Net Premium Written General and Administrative Expenses Reinsurance $ 205.2 $ 2,148.4 $ 688.6 $ 1,118.8 $ 705.2 $ 221.6 $ 1,199.0 $ 121.3 Insurance 85.6 2,165.3 827.6 1,291.7 988.1 192.5 1,388.7 211.8 Total $ 290.8 $ 4,313.7 $ 1,516.2 $ 2,410.5 $ 147.5 $ 1,693.3 $ 414.1 $ 2,587.7 $ 333.1 Year to date December 31, 2020 Deferred Policy Acquisition Costs Net Reserves for Losses and LAE Net Net Premiums Earned Net Investment Income Losses and LAE Expenses Policy Acquisition Expenses Net Premium Written General and Administrative Expenses Reinsurance $ 206.8 $ 2,095.7 $ 617.6 $ 1,287.7 $ 958.6 $ 246.0 $ 1,297.7 $ 110.8 Insurance 99.8 1,874.4 746.1 1,239.8 882.2 219.7 1,280.1 197.2 Total $ 306.6 $ 3,970.1 $ 1,363.7 $ 2,527.5 $ 154.6 $ 1,840.8 $ 465.7 $ 2,577.8 $ 308.0

Schedule IV - Reinsurance

Schedule IV - Reinsurance	12 Months Ended
	Dec. 31, 2022
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Schedule IV - Reinsurance	SCHEDULE IV - REINSURANCE For the Twelve Months Ended December 31, 2022, 2021 and 2020 Premiums Written Direct Assumed Ceded Net Amount ($ in millions) 2022 $ 2,531.7 $ 1,807.0 $ (1,442.7) $ 2,896.0 2021 $ 2,341.4 $ 1,597.0 $ (1,350.7) $ 2,587.7 2020 $ 2,042.1 $ 1,656.4 $ (1,120.7) $ 2,577.8 Premiums Earned Gross Amount Assumed From Ceded to Other Companies Net Amount Percentage of Amount Assumed to Net ($ in millions, except for percentages) 2022 $ 2,370.8 $ 1,617.2 $ (1,299.3) $ 2,688.7 60.1 % 2021 $ 2,139.1 $ 1,479.2 $ (1,207.8) $ 2,410.5 61.4 % 2020 $ 2,026.4 $ 1,612.0 $ (1,110.9) $ 2,527.5 63.8 %

Schedule V - Valuation and Qual

Schedule V - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2022
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule V - Valuation and Qualifying Accounts	SCHEDULE V - VALUATION AND QUALIFYING ACCOUNTS For the Twelve Months Ended December 31, 2022, 2021 and 2020 The following table shows the movement in the Company’s bad debt provision during the twelve months ended December 31, 2022, 2021 and 2020: Balance at Charged to Costs and Expenses Charged to Other Accounts Deductions Balance at Provisions for Bad Debt ($ in millions) 2022 Premiums receivable from underwriting activities $ 30.2 $ (5.2) $ — $ — $ 25.0 Reinsurance $ — $ — $ — $ — $ — 2021 Premiums receivable from underwriting activities $ 34.0 $ (3.8) $ — $ — $ 30.2 Reinsurance $ — $ — $ — $ — $ — 2020 Premiums receivable from underwriting activities $ 23.0 $ 11.0 $ — $ — $ 34.0 Reinsurance $ — $ — $ — $ — $ —

History and Organization_2

History and Organization	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
History and Organization	History and Organization History and Organization. Aspen Insurance Holdings Limited (“Aspen Holdings”) was incorporated on May 23, 2002 as a holding company headquartered in Bermuda. We underwrite specialty insurance and reinsurance on a global basis through our Operating Subsidiaries (as defined below) based in Bermuda, the United States and the United Kingdom: Aspen Bermuda Limited (“Aspen Bermuda”), Aspen Specialty Insurance Company (“Aspen Specialty”), Aspen American Insurance Company (“AAIC”), Aspen Insurance UK Limited (“Aspen UK”) and Aspen Underwriting Limited (“AUL”) (as corporate member of our Lloyd’s operations, Syndicate 4711, which are managed by Aspen Managing Agency Limited (“AMAL”) (together, “Aspen Lloyd’s”)), each referred to herein as an “Operating Subsidiary” and collectively referred to as the “Operating Subsidiaries”. We also have branches in Australia, Canada, Singapore and Switzerland. We established Aspen Capital Management, Ltd. (“ACML”) and other related entities (collectively, “ACM”) to leverage our existing underwriting franchise, increase our operational flexibility and provide third-party investors direct access to our capital markets and underwriting expertise. References to the “Company,” the “Group,” “we,” “us” or “our” refer to Aspen Holdings or Aspen Holdings and its consolidated subsidiaries. Since February 2019, the Company has been a wholly-owned subsidiary of Highlands Bermuda Holdco, Ltd. (“Parent”), which holds all of the Company’s ordinary shares. Parent, a Bermuda exempted company, is an affiliate of certain investment funds managed by affiliates of Apollo Global Management, Inc., a leading global investment manager (collectively with its subsidiaries, “Apollo”). The Company’s preference shares and depositary shares are listed on the New York Stock Exchange (“NYSE”) under the following symbols: AHL PRC, AHL PRD and AHL PRE. History and Organization History and Organization. Aspen Insurance Holdings Limited (“Aspen Holdings”) was incorporated on May 23, 2002 as a holding company headquartered in Bermuda. We underwrite specialty insurance and reinsurance on a global basis through our Operating Subsidiaries (as defined below) based in Bermuda, the United States and the United Kingdom: Aspen Bermuda Limited (“Aspen Bermuda”), Aspen Specialty Insurance Company (“Aspen Specialty”), Aspen American Insurance Company (“AAIC”), Aspen Insurance UK Limited (“Aspen UK”) and Aspen Underwriting Limited (“AUL”) (as corporate member of our Lloyd’s operations, Syndicate 4711, which are managed by Aspen Managing Agency Limited (“AMAL”) (together, “Aspen Lloyd’s”)), each referred to herein as an “Operating Subsidiary” and collectively referred to as the “Operating Subsidiaries”. We also have branches in Canada, Singapore and Switzerland. We established Aspen Capital Management, Ltd. (“ACML”) and other related entities (collectively, “ACM”) to leverage our existing underwriting franchise, increase our operational flexibility and provide third-party investors direct access to our capital markets and underwriting expertise. References to the “Company,” the “Group,” “we,” “us” or “our” refer to Aspen Holdings or Aspen Holdings and its consolidated subsidiaries. Since February 2019, the Company has been a wholly-owned subsidiary of Highlands Bermuda Holdco, Ltd. (“Parent”), which holds all of the Company’s ordinary shares. Parent, a Bermuda exempted company, is an affiliate of certain investment funds managed by affiliates of Apollo Global Management, Inc., a leading global investment manager (collectively with its subsidiaries, “Apollo”). The Company’s preference shares and depositary shares are listed on the New York Stock Exchange (“NYSE”) under the following symbols: AHL PRC, AHL PRD and AHL PRE.

Basis of Preparation and Sign_2

Basis of Preparation and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Preparation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies The consolidated financial statements of Aspen Holdings are prepared in accordance with United States Generally Accepted Accounting Principles (“U.S. GAAP”) and are presented on a consolidated basis including the transactions of all operating subsidiaries in which the Company has a controlling financial interest and variable interest entities (“VIE”) in which the Company is considered to be the primary beneficiary. Transactions between Aspen Holdings and its subsidiaries are eliminated within the consolidated financial statements. The consolidated financial statements have been prepared on a going concern basis. (a) Use of Estimates Assumptions and estimates made by management have a significant effect on the amounts reported within the consolidated financial statements. The most significant of these relate to losses and loss adjustment expenses, reinsurance recoverables, gross written premiums and commissions which have not been reported to the Company such as those relating to proportional treaty reinsurance contracts, unrecognized tax benefits, recoverability of deferred tax assets, the fair value of derivatives and the fair value of other and privately-held investments. All material assumptions and estimates are regularly reviewed and adjustments made as necessary but actual results could be significantly different from those expected when the assumptions or estimates were made. (b) Accounting for Insurance and Reinsurance Operations Premiums Earned. Premiums are recorded as written on the inception date of a policy. Premiums are recognized as revenues proportionately over the coverage period. Premiums earned are recorded in the consolidated statements of operations, net of the cost of purchased reinsurance. Premiums written which are not yet recognized as earned premium are recorded in the consolidated balance sheet as unearned premiums. Written and earned premiums and the related costs include estimates for premiums which have not been finally determined. These relate mainly to contractual provisions for the payment of adjustment or additional premiums, premiums payable under proportional treaties and delegated underwriting authorities, and reinstatement premiums. Adjustment and additional premiums are premiums charged which relate to experience during the policy term. The proportion of adjustable premiums included in the premium estimates varies between business lines with the largest adjustment premiums being in property and casualty reinsurance, marine, aviation and energy insurance and the smallest in property and casualty insurance. Premiums under proportional treaty contracts and delegated underwriting authorities are generally not reported to the Company until after the reinsurance coverage is in force. As a result, an estimate of these “pipeline” premiums is recorded. The Company estimates pipeline premiums based on projections of ultimate premium taking into account reported premiums and expected development patterns. Reinstatement premiums on assumed excess of loss reinsurance contracts are provided based on experience under such contracts. Reinstatement premiums are the premiums charged for the restoration of the reinsurance limit of an excess of loss contract to its full amount after payment by the reinsurer of losses as a result of an occurrence. The original premiums are recognized as revenue in full at the date of loss, with the reinstatement premiums recognized as revenue over the remaining cover term. Reinstatement premiums provide future insurance cover for the remainder of the initial policy term. An allowance for uncollectible premiums is established for possible non-payment of premium receivables, as deemed necessary. Credit Losses on Underwriting Premiums Receivable. Underwriting premium receivable balances are reported net of an allowance for expected credit losses. The allowance, based on ongoing review and monitoring of amounts outstanding, historical loss data, including write-offs and other relevant factors, is charged to net income in the period the receivable is recorded and revised in subsequent periods to reflect changes in the Company’s estimate of expected credit losses. Credit risk is partially mitigated by the Company’s ability to cancel the policy if the policyholder does not pay the premium. Losses and Loss Adjustment Expenses. Losses represent the amount paid or expected to be paid to claimants in respect of events that have occurred on or before the balance sheet date. The costs of investigating, resolving and processing these claims are known as loss adjustment expenses (“LAE”). The consolidated statements of operations records these losses net of reinsurance, meaning that gross losses and loss adjustment expenses incurred are reduced by the amounts recovered or expected to be recovered under reinsurance contracts. Reinsurance. Written premiums, earned premiums, incurred claims, LAE and the acquisition costs all reflect the net effect of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the Company’s acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance arises from contracts under which other insurance companies agree to share certain risks with the Company. Reinsurance accounting is followed when there is significant timing risk, significant underwriting risk and a reasonable possibility of significant loss. Outward reinsurance premiums, which are paid when the Company purchases reinsurance or retrocessional coverage, are accounted for using the same accounting methodology as the Company uses for inwards premiums. Premiums payable under reinsurance contracts that operate on a “losses occurring during” basis are expensed over the period of coverage while those arising from “risks attaching during” policies are expensed over the earnings period of the underlying premiums written from the reinsured business. Adjustment premiums and reinstatement premiums in relation to outward reinsurance are accrued when it is determined that the ultimate losses will trigger a payment and recognized within premiums payable. Reinsurance and retrocession does not isolate the ceding company from its obligations to policyholders. In the event that a reinsurer or retrocessionaire fails to meet its obligations, the ceding company’s obligations remain. Accounting for Retroactive Reinsurance Agreements. Retroactive reinsurance agreements are reinsurance agreements under which a reinsurer agrees to reimburse the Company as a result of past insurable events. For retroactive reinsurance purchased by the Company, the excess of the amounts ultimately collectible under the agreement over the consideration paid is recognized as a deferred gain liability which is amortized into income over the settlement period of the ceded reserves once the paid losses have exceeded the minimum retention. The amount of the deferral is recalculated each period based on actual loss payments and updated estimates of ultimate losses. If the consideration paid exceeds the ultimate losses collectible under the agreement, the net loss on the retroactive reinsurance agreement is recognized within income immediately. Premiums payable for retroactive reinsurance coverage and meeting the conditions of reinsurance accounting are reported as reinsurance recoverables to the extent that those amounts do not exceed recorded liabilities relating to underlying reinsurance contracts. Premiums paid in excess of accounts receivable are charged to income. Reserves. Insurance reserves are established for the total unpaid cost of claims and LAE in respect of events that have occurred by the balance sheet date, including the Company’s estimates of the total cost of claims incurred but not yet reported (“IBNR”). Claim reserves are reduced for estimated amounts of salvage and subrogation recoveries. Estimated amounts recoverable from reinsurers on unpaid losses and LAE are reflected as assets. For reported claims, reserves are established on a case-by-case basis within the parameters of coverage provided in the insurance policy or reinsurance agreement. For IBNR claims, reserves are estimated using a number of established actuarial methods to establish a range of estimates from which a management best estimate is selected. Both case and IBNR reserve estimates consider variables such as past loss experience, changes in legislative conditions, changes in judicial interpretation of legal liability, policy coverages and inflation. As many of the coverages underwritten involve claims that may not be ultimately settled for many years after they are incurred, subjective judgments as to the ultimate exposure to losses are an integral and necessary component of the loss reserving process. The Company regularly reviews its reserves, using a variety of statistical and actuarial techniques to analyze current claims costs, frequency and severity data, and prevailing economic, social and legal factors. Reserves established in prior periods are adjusted as claim experience develops and new information becomes available. Adjustments to previously estimated reserves are reflected in the financial results of the period in which the adjustments are made. The process of estimating required reserves does, by its very nature, involve considerable uncertainty. The level of uncertainty can be influenced by factors such as the existence of coverage with long duration payment patterns and changes in claims handling practices, as well as the factors noted above. Ultimate actual payments for claims and LAE could turn out to be significantly different from the Company’s estimates. Credit Losses on Reinsurance Recoverables. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability with the reinsured business. The Company evaluates the financial condition of its reinsurers and retrocessionaires, and monitors concentration of credit risk to minimize its exposure to significant losses from individual reinsurers. To further reduce credit exposure on reinsurance recoverables, the Company has received collateral, including letters of credit and trust accounts, from certain reinsurers. Following the adoption of ASC 326, an allowance is established for expected credit losses to be recognized over the life of the reinsurance recoverable. The allowance considers the current financial strength of the individual reinsurer and the amount of collateral held. Acquisition Costs. The costs directly related to writing a (re)insurance policy are referred to as acquisition expenses and include commissions, premium taxes and profit commissions. With the exception of profit commissions, these expenses are incurred when a policy is issued, and only the costs directly related to the successful acquisition of new and renewal insurance and reinsurance contracts are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. Profit commissions are estimated and accrued based on the related performance criteria evaluated at the balance sheet date, with subsequent changes to those estimates recognized when they occur. Commissions received related to reinsurance premiums ceded are netted against broker commissions in determining acquisition costs eligible for deferral. On a regular basis a premium deficiency analysis is performed of the deferred acquisition costs in relation to the expected recognition of revenues, including anticipated investment income, and adjustments, if any, are reflected as period costs. Should the analysis indicate that the acquisition costs are unrecoverable, further analyses are performed to determine if a reserve is required to provide for losses which may exceed the related unearned premium. General and Administrative Expenses. These costs represent the expenses incurred in running the business and include, but are not limited to compensation costs for employees, rental costs, IT development and professional and consultancy fees. General and administrative costs directly attributable to the successful acquisition of business are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. When reporting the results for its business segments, the Company includes expenses which are directly attributable to the segment plus an allocation of central administrative costs. Corporate Expenses. Corporate expenses are not allocated to the Company’s business segments as they typically do not fluctuate with the levels of premium written and are related to the Company’s operations which include group executive costs, group finance costs, group legal and actuarial costs and certain strategic and other costs. (c) Accounting for Investments, Cash and Cash Equivalents Fixed Income Securities. The fixed income securities portfolio comprises securities issued by governments and government agencies, corporate bonds, mortgage and other asset-backed securities and bank loans. Investments in fixed income securities are classified as available for sale or trading and are reported at estimated fair value in the consolidated balance sheet. Investment transactions are recorded on the trade date with balances pending settlement reflected in the consolidated balance sheet under receivables for securities sold and other payables for securities purchased, respectively. Fair values are based on quoted market prices and other data provided by third-party pricing services. Short-term Investments. Short-term investments primarily comprise highly liquid debt securities with a maturity greater than three months but less than one year from the date of purchase and are held as part of the investment portfolio of the Company. Short-term investments are classified as either trading or available for sale and reported at estimated fair value. Catastrophe Bonds. Investments in catastrophe bonds are classified as trading and are reported on the consolidated balance sheet at estimated fair value. The fair values are based on independent broker-dealer quotes. Privately-held Investments. The Company’s privately-held investments primarily comprise commercial mortgage loans, middle market loans, asset-backed securities, global corporate securities and equity securities. These investments are classified as trading and are reported on the consolidated balance sheet at estimated fair value. Privately-held investments are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are primarily determined using internally developed discounted cash flow models. Interest income is accrued on the principal amount of the loan based on its contractual interest rate subject to it being probable that we will receive interest on that particular underlying loan. Interest income, amortization of premiums and discounts, and prepayment fees are reported in net investment income on the consolidated statements of income. Other Investments, Equity Method. Other investments represent the Company’s investments that are recorded using the equity method of accounting. Adjustments to the fair value of these investments are made based on the net asset value of the investment. Other Investments. Other investments represent the Company’s investments in real estate funds and other special purpose vehicles. Adjustments to the fair value are made based on the net asset value of the investment. Cash and Cash Equivalents. Cash and cash equivalents are reported at fair value. Cash and cash equivalents comprise cash on hand, deposits held on call with banks and other short-term highly liquid investments due to mature within three months from the date of purchase and which are subject to insignificant risk of change in fair value. Gains and Losses. Realized gains or losses on the sale of investments are determined on the basis of the first in first out cost method and are recorded in revenue or expenses respectively. Unrealized gains and losses represent the difference between the cost, or the cost as adjusted by amortization of any difference between its cost and its redemption value (“amortized cost”), of the security and its fair value at the reporting date and are included within other comprehensive income for securities classified as available for sale and in realized and unrealized investment gains or losses in the consolidated statement of operations for securities classified as trading. Credit Losses on Available for Sale Debt Securities . Following Aspen’s adoption of ASU 2016-13 “Financial Instruments - Credit Losses (Topic 326)” , effective January 1, 2020, current expected credit losses (CECL) are recognized through an allowance account for available for sale debt securities, thereby permitting reversals of previously recognized credit losses through net income in the period they occur. Write-offs (of any previously recognized allowance for credit losses) are recorded when amounts are deemed uncollectible, or Aspen intends to sell (or more likely than not will be required to sell) the debt security before recovery of the amortized cost basis. The amortized cost basis will be written down to the debt securities fair value through earnings. Credit losses are limited to the difference between the debt securities amortized cost basis and fair value (‘fair-value floor’). Any decline in the debt securities fair value below the amortized cost basis that is not a result of a credit loss is recorded through other comprehensive income, net of applicable taxes. Our credit loss models employ a discounted cash flow approach to evaluate whether a credit loss exists at the individual security level and are reviewed at each reporting period. This analysis excludes investments in U.S. Government / Agency bonds and U.S. Government Agency mortgage-backed securities due to being of ‘high credit quality’ based on the absence of risk. Available for sale debt securities that were initially purchased with credit deterioration (PCD), the amortized cost basis shall be considered to be the purchase price, plus any allowance for credit losses. Estimated credit losses shall be discounted at the rate that equates the present value of the purchaser’s estimate of the security’s future cash flows with the purchase price of the asset. Holding gains or losses are recognition through other comprehensive income, net of applicable taxes. No changes in the estimate of credit losses have taken place during the period. Net Investment Income. Investment income includes amounts received and accrued in respect of periodic interest (“coupons”) payable to the Company by the issuer of fixed income securities, equity dividends and interest credited on cash and cash equivalents. It also includes amortization of premium and accretion of discount in respect of fixed income securities. Investment income also includes changes in fair value from investments in real estate funds. Investment management and custody fees are charged against net investment income reported in the consolidated statement of operations. (d) Accounting for Derivative Financial Instruments The Company enters into derivative instruments such as interest rate swaps and forward exchange contracts in order to manage certain market and credit risks. The Company records derivative instruments at fair value on the Company’s consolidated balance sheet as either assets or liabilities, depending on their rights and obligations. The accounting for the gain or loss due to the changes in the fair value of these instruments is dependent on whether the derivative qualifies as a hedge. If the derivative does not qualify as a hedge, the gains or losses are reported in the consolidated statement of operations when they occur. If the derivative qualifies as a hedge, the accounting treatment varies based on the type of risk being hedged. Gains and losses on the effective portion of such contracts are recognized in other comprehensive income. As the contracts settle, the realized gain or loss is reclassified from other comprehensive income into the consolidated statement of operations. The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangements is considered an embedded derivative and accounted for as an option-based derivative. Since the economic characteristics and risks of an embedded derivative feature are not clearly and closely related to the economic characteristics and risks of the host contract, the embedded derivative is bifurcated and accounted for separately at fair value. The Company records subsequent changes in the embedded derivative fair value in the consolidated statement of operations. (e) Accounting for Intangible Assets Intangible assets are held in the consolidated balance sheet at cost less amortization and impairment. Amortization applies on a straight-line basis in respect of assets having a finite estimated useful economic life. Finite intangibles are assessed on an annual basis for impairment, or more frequently where circumstances indicate the carrying value may not be recoverable. For intangible assets considered to have an indefinite life, the Company performs a qualitative assessment annually to determine whether it is more likely than not that an intangible asset is impaired. Goodwill is assessed annually for impairment or more frequently if circumstances indicate an impairment may have occurred. (f) Accounting for Office Properties and Equipment Office properties and equipment are reported at cost less accumulated depreciation. These assets are depreciated on a straight-line basis over the estimated useful lives of the assets. Computer equipment is depreciated between three IT development costs that are directly associated with the development of identifiable and unique software products and that are anticipated to generate economic benefits exceeding costs beyond one year, are recognized within office properties and equipment. Costs include external consultants’ fees, certain qualifying internal staff costs and other costs incurred to develop software programs. Software is depreciated over their estimated useful life, between three and five years, on a straight-line basis and is subject to impairment testing annually. Depreciation commences when the asset becomes operational. Other non-qualifying costs are expensed as incurred. (g) Accounting for Leases In the ordinary course of the business, the Company renews and enters into new leases for office real estate and other assets. At the lease inception date, the Company determines whether a contract contains a lease and recognizes operating lease Right-of-use assets and operating lease liabilities based on the present value of future minimum lease payments. As our leases do not provide an implicit interest rate, we use our incremental borrowing rate based on the information available at the commencement date to determine the present value of future payments. For all office real estate leases, rent incentives, including reduced-rent and rent free periods and contractually agreed rent increases during the lease term, have been included when determining the present value of future cash flows. Right-of-use operating lease assets are reported at cost less accumulated depreciation on the consolidated balance sheet and depreciated over the lease term. The Company does not record office property and equipment leases with an initial term of 12 months or less (short-term) in the Company's consolidated balance sheets. Such short-term leases are expensed through the consolidated statement of operations. Right-of-use operating lease assets are tested for impairments whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. If the carrying value of an asset is impaired, it is reduced to the recoverable amount by an immediate charge to the income statement. The recoverable amount is the higher of an asset’s fair value less costs to sell and value in use. (h) Accounting for Foreign Currencies Translation The reporting currency of the Company is the U.S. Dollar. Effective January 1, 2022, management reassessed its functional currency determination in accordance with ASC 830, Foreign Currency Matters, as a result of significant changes in the Group’s economic facts and circumstances, and concluded that the functional currency of certain of its foreign operations had changed. Consequently, the Company has concluded that the U.S. Dollar is now the functional currency for all its branches and overseas entities. The change in the Company’s functional currency determination has been applied on a prospective basis in accordance with ASC 830. Therefore, any translation gains and losses that were previously recorded in accumulated other comprehensive income through December 31, 2021 remain unchanged through December 31, 2021. From January 1, 2022, any net realized and unrealized gains/(losses) on translation are recognized in the consolidated statements of operations and other comprehensive income (loss). Investments classified as available-for-sale are recorded at fair value, the portion attributable to movements in exchange rates continues to be included within accumulated other comprehensive income. Transactions in currencies other than the functional currency are measured at the exchange rate prevailing at the date of the transaction. Monetary assets and liabilities denominated in non-functional currencies are remeasured at the exchange rate prevailing at the balance sheet date and any resulting foreign exchange gains or losses are reflected in the consolidated statement of operations. Non-monetary assets and liabilities are remeasured to functional currency at historic exchange rates. (i) Accounting for Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. When the Company does not believe that, on the basis of available information, it is more likely than not that deferred tax assets will be fully recovered, it recognizes a valuation allowance against its deferred tax assets to reduce the deferred tax assets to the amount more likely than not to be realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Furthermore, a tax benefit from a tax position may be recognized in the financial statements only if it is more-likely-than-not that the position is sustainable, based solely on its technical merits and consideration of the relevant tax authority’s widely understood administrative practices and precedents. The Company applies a portfolio approach to release the income tax effects in accumulated other comprehensive income. Under this approach, the income tax effects upon the sale of an available-for-sale debt security, settlement of hedged transactions and upon foreign currency translation adjustments for each period, are determined under the intraperiod tax allocation approach. Any tax effects remaining in accumulated other comprehensive income are only released when the entire portfolio is liquidated, sold or extinguished. (j) Accounting for Preference Shares The Company had at the balance sheet date in issue three classes of preference shares. The Company has no obligation to pay interest on these securities but they carry entitlements to dividends payable at the discretion of the Board of Directors. In the event of non-payment of dividends for six consecutive periods, holders of preference shares have director appointment rights. The preference shares are therefore accounted for as equity instruments and included within total shareholders’ equity. (k) Accounting for Long-Term Incentive Plans The Company operates an employee long-term incentive plan, comprised of Performance Units and Exit Units, the terms and conditions of which are described in Note 16. The Company applies a fair-value based measurement method in calculating the compensation costs of Performance Units which are recognized on a straight-line basis over the vesting period. (l) Accounting for Business Combinations The Company accounts for a transaction as a business combination where the assets acquired and liabilities assumed following a transaction constitute a business. An acquired entity must have inputs and processes that make it capable of generating a return or economic benefit to be considered a business. If the assets acquired are not a business, the Company accounts the transaction as an asset acquisition. The Company recognizes and measures at fair value 100 percent of the assets and liabilities of any acquired business. Goodwill is recognized and measured as the difference between the consideration paid or payable less the fair value of assets acquired. The Company accounts for the disposal of subsidiary undertakings when it ceases to control the subsidiary’s assets and liabilities or the group of assets. A gain or loss is recognized and measured as the difference between the fair value of consideration received or receivable and the value of assets, liabilities and equity components de-recognized, related to that subsidiary or group of assets when deconsolidated. Costs that are directly related to a business combination transaction are expensed in the periods in which the costs are incurred and the services are received. (m) Accounting Pronouncements Accounting Pronouncements Adopted In March 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326 )”. This update is as a result of a post implementation review done on the issued ASU No.2016-13 , Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , addressing “troubled debt restructuring by creditors” and “vintage disclosures”. This update will be effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Accounting Pronouncements Not Yet Adopted In March 2022, the FASB issued Accounting Standards Update No. ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging, Portfolio Layer Method ”. This update addresses concerns from entities and practitioners regarding the ‘last-of-layer’ method of accounting incorporated in update No. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” , issued on 28 August, 2017. This method is meant to achieve fair value hedge accounting for interest rate risk hedges of portfolios of ‘prepayable financial assets’. This ASU will be effective for fiscal years beginning after December 15, 2023 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In June 2022, the FASB issued Accounting Standards Update No. ASU 2022-03, “Fair Value Measurement (Topic 820 )”. This update is for entities that have investments in equity securities, measured at fair value, which are subject to a contractual sale restriction. This update will be effective for fiscal years beginning after December 15, 2024 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In September 2022, the FASB issued Accounting Standards Update No. ASU 2022-04, “Liabilities- Supplier Finance Programs (Subtopic 405-50)” . The update has been issued to enhance the transparency of supplier finance progr

Segment Reporting_2

Segment Reporting	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company manages its underwriting operations as two business segments: Aspen Reinsurance and Aspen Insurance. The Company has determined its reportable segments by taking into account the manner in which management makes operating decisions and assesses operating performance. Profit or loss for each of the Company’s business segments is measured by underwriting income or loss. Underwriting profit is the excess of net earned premiums over the sum of losses and loss expenses, acquisition costs and general and administrative expenses. Underwriting income or loss provides a basis for management to evaluate the segment’s underwriting performance. Reinsurance Segment. The reinsurance segment consists of property catastrophe reinsurance, other property reinsurance, casualty reinsurance and specialty reinsurance. Insurance Segment. The insurance segment consists of first party and specialty insurance, casualty and liability insurance and financial and professional lines insurance. Additionally, the insurance segment includes Aspen Underwriting Limited’s participation as a corporate member in Carbon Syndicate 4747 (“Carbon Syndicate”). Non-underwriting Disclosures. The Company provides additional disclosures for corporate and other (non-operating) income and expenses. Corporate and other income and expenses include: corporate expenses, net investment income, net realized and unrealized investment gains or losses, other strategic and other costs, changes in fair value of derivatives or the loan notes issued by variable interest entities, interest expenses, net realized and unrealized foreign exchange gains or losses, asset impairments and income taxes. These income and expense items are not allocated to the Company’s business segments as they are not directly related to the Company’s business segment operations and is consistent with how management measures the performance of its segments. The Company does not allocate its assets by business segment. The Company uses underwriting ratios as measures of performance. The loss ratio is the ratio of losses and loss adjustment expenses to net earned premiums. The acquisition cost ratio is the ratio of acquisition costs to net earned premiums. The general and administrative expense ratio is the ratio of general and administrative expenses to net earned premiums. The combined ratio is the sum of the loss ratio, the acquisition cost ratio and the general and administrative expense ratio. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for the twelve months ended December 31, 2022, 2021 and 2020: Twelve Months Ended December 31, 2022 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,807.0 $ 2,531.7 $ 4,338.7 Net written premiums 1,426.4 1,469.6 2,896.0 Gross earned premiums 1,617.2 2,370.8 3,988.0 Net earned premiums 1,251.8 1,436.9 2,688.7 Underwriting Expenses Losses and loss adjustment expenses 770.3 909.7 1,680.0 Acquisition costs 252.4 179.4 431.8 General and administrative expenses 142.5 244.0 386.5 Underwriting income 86.6 103.8 190.4 Corporate expenses (71.7) Non-operating expenses (1) (36.0) Net investment income 188.1 Realized and unrealized investment gains 5.0 Realized and unrealized investment losses (182.6) Change in fair value of derivatives (80.5) Interest expense (43.7) Net realized and unrealized foreign exchange gains 15.9 Other income 8.2 Other expenses (20.1) (Loss) before income taxes (27.0) Income tax benefit 78.1 Net income $ 51.1 Net reserves for loss and loss adjustment expenses $ 1,360.7 $ 1,452.5 $ 2,813.2 Ratios Loss ratio 61.5 % 63.3 % 62.5 % Acquisition cost ratio 20.2 12.5 16.1 General and administrative expense ratio 11.4 17.0 14.4 Expense ratio 31.6 29.5 30.5 Combined ratio 93.1 % 92.8 % 93.0 % ________________ (1) Non-operating expenses includes $32.7 million in relation to fixed assets written off, $10.0 million of severance, consulting and professional services in relation to non-recurring projects and other costs, offset by $6.7 million of write backs related to leased office space. Twelve Months Ended December 31, 2021 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,597.0 $ 2,341.4 $ 3,938.4 Net written premiums 1,199.0 1,388.7 2,587.7 Gross earned premiums 1,479.2 2,139.1 3,618.3 Net earned premiums 1,118.8 1,291.7 2,410.5 Underwriting Expenses Losses and loss adjustment expenses 705.2 988.1 1,693.3 Acquisition costs 221.6 192.5 414.1 General and administrative expenses 121.3 211.8 333.1 Underwriting income/(loss) 70.7 (100.7) (30.0) Corporate expenses (64.3) Non-operating expenses (1) (20.6) Net investment income 147.5 Realized and unrealized investment gains 56.2 Realized and unrealized investment losses (47.4) Change in fair value of derivatives (35.9) Interest expense (14.3) Net realized and unrealized foreign exchange gains 40.0 Other income 14.7 Other expenses (10.8) Income before income taxes 35.1 Income tax (expense) (5.3) Net income $ 29.8 Net reserves for loss and loss adjustment expenses $ 2,148.4 $ 2,165.3 $ 4,313.7 Ratios Loss ratio 63.0 % 76.5 % 70.2 % Acquisition cost ratio 19.8 14.9 17.2 General and administrative expense ratio 10.8 16.4 13.8 Expense ratio 30.6 31.3 31.0 Combined ratio 93.6 % 107.8 % 101.2 % ________________ (1) Non-operating expenses includes $19.3 million of costs related to consulting and professional services in relation to non-recurring projects and other costs, $0.4 million of impairment charges related to lease assets as a result of exiting certain office space and $0.9 million of amortization of intangible assets and other non-operating expenses. Twelve Months Ended December 31, 2020 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,656.4 $ 2,042.1 $ 3,698.5 Net written premiums 1,297.7 1,280.1 2,577.8 Gross earned premiums 1,612.0 2,026.4 3,638.4 Net earned premiums 1,287.7 1,239.8 2,527.5 Underwriting Expenses Losses and loss adjustment expenses 958.6 882.2 1,840.8 Acquisition costs 246.0 219.7 465.7 General and administrative expenses 110.8 197.2 308.0 Underwriting (loss) (27.7) (59.3) (87.0) Corporate expenses (70.2) Non-operating expenses (1) (32.7) Net investment income 154.6 Realized and unrealized investment gains 98.5 Realized and unrealized investment losses (27.4) Change in fair value of derivatives (65.1) Interest expense (33.9) Net realized and unrealized foreign exchange (losses) (13.8) Other income 49.8 Other expenses (10.8) (Loss) before income taxes (38.0) Income tax (expense) (18.4) Net (loss) $ (56.4) Net reserves for loss and loss adjustment expenses $ 2,095.7 $ 1,874.4 $ 3,970.1 Ratios Loss ratio 74.4 % 71.1 % 72.8 % Acquisition cost ratio 19.1 17.7 18.4 General and administrative expense ratio 8.6 15.9 12.2 Expense ratio 27.7 33.6 30.6 Combined ratio 102.1 % 104.7 % 103.4 % ________________ (1) Non-operating expenses includes $18.2 million of expenses related to severance, retention and other costs, $12.9 million of impairment charges related to lease assets as a result of sub-leasing certain office space and $1.6 million of amortization of intangible assets and other non-operating expenses. Geographical Areas . The following summary presents the Company’s gross written premiums based on the location of the insured risk for the twelve months ended December 31, 2022, 2021 and 2020. For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Australia/Asia $ 257.5 $ 275.8 $ 259.7 Europe 194.5 140.6 92.5 United Kingdom 485.8 393.2 369.0 United States & Canada (1) 2,715.7 2,301.8 2,267.5 Worldwide excluding United States (2) 24.2 31.5 23.1 Worldwide including United States (3) 541.7 592.2 501.2 Other (4) 119.3 203.3 185.5 Total $ 4,338.7 $ 3,938.4 $ 3,698.5 ________________ (1) “United States and Canada” comprises individual policies that insure risks specifically in the United States and/or Canada, but not elsewhere. (2) “Worldwide excluding the United States” consists of individual policies that insure global risks with the specific exclusion of the United States. (3) “Worldwide including the United States” consists of individual policies that insure global risks with the specific inclusion of the United States. (4) “Other” comprises individual policies that insure risk in other countries including, but not limited to, the Caribbean, South America and Middle East. Segment Reporting The Company manages its underwriting operations as two business segments: Aspen Reinsurance and Aspen Insurance. The Company has determined its reportable segments by taking into account the manner in which management makes operating decisions and assesses operating performance. Profit or loss for each of the Company’s business segments is measured by underwriting income or loss. Underwriting profit is the excess of net earned premiums over the sum of losses and loss expenses, acquisition costs and general and administrative expenses. Underwriting income or loss provides a basis for management to evaluate the segment’s underwriting performance. Reinsurance Segment. The reinsurance segment consists of property catastrophe reinsurance, other property reinsurance, casualty reinsurance and specialty reinsurance. For a more detailed description of this business segment, refer to “Business—Our Business—Reinsurance” in this prospectus. Insurance Segment. The insurance segment consists of first party insurance, specialty insurance, casualty and liability insurance and financial and professional lines insurance. Additionally, the insurance segment includes Aspen Underwriting Limited’s participation as a corporate member in Carbon Syndicate 4747 (“Carbon Syndicate”). For a more detailed description of this business segment, refer to “Business—Our Business—Insurance” in this prospectus. Non-underwriting Disclosures. The Company provides additional disclosures for corporate and other (non-operating) income and expenses. Corporate and other income and expenses include: corporate expenses, net investment income, net realized and unrealized investment gains or losses, other strategic and other costs, changes in fair value of derivatives or the loan notes issued by variable interest entities, interest expenses, net realized and unrealized foreign exchange gains or losses, asset impairments and income taxes. These income and expense items are not allocated to the Company’s business segments as they are not directly related to the Company’s business segment operations and is consistent with how management measures the performance of its segments. The Company does not allocate its assets by business segment. The Company uses underwriting ratios as measures of performance. The loss ratio is the ratio of losses and loss adjustment expenses to net earned premiums. The acquisition cost ratio is the ratio of acquisition costs to net earned premiums. The general and administrative expense ratio is the ratio of general and administrative expenses to net earned premiums. The combined ratio is the sum of the loss ratio, the acquisition cost ratio and the general and administrative expense ratio. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for six months ended June 30, 2023 and 2022: Six Months Ended June 30, 2023 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 875.7 $ 1,249.5 $ 2,125.2 Net written premiums 605.0 745.5 1,350.5 Net earned premiums 572.0 715.4 1,287.4 Underwriting Expenses Losses and loss adjustment expenses 297.2 419.9 717.1 Acquisition costs 105.7 87.2 192.9 General and administrative expenses 58.4 110.6 169.0 Underwriting income 110.7 97.7 208.4 Corporate and other expenses (1) (53.1) Non-operating expenses (10.6) Net investment income 129.4 Realized and unrealized investment gains 36.1 Realized and unrealized investment losses (18.1) Change in fair value of derivatives 19.6 Interest expense (42.9) Net realized and unrealized foreign exchange losses (13.7) Income before income taxes 255.1 Income tax (expense) (36.2) Net income $ 218.9 Net reserves for loss and loss adjustment expenses $ 1,441.2 $ 1,641.7 $ 3,082.9 Ratios Loss ratio 52.0 % 58.7 % 55.7 % Acquisition cost ratio 18.5 12.2 15.0 General and administrative expense ratio 10.2 15.5 13.1 Expense ratio 28.7 27.7 28.1 Combined ratio 80.7 % 86.4 % 83.8 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately. Six Months Ended June 30, 2022 Reinsurance Insurance Total ( $ in millions) Underwriting Revenues Gross written premiums $ 1,045.6 $ 1,305.7 $ 2,351.3 Net written premiums 783.7 722.4 1,506.1 Net earned premiums 600.8 726.4 1,327.2 Underwriting Expenses Losses and loss adjustment expenses 369.0 398.7 767.7 Acquisition costs 124.1 92.4 216.5 General and administrative expenses 69.7 116.8 186.5 Underwriting income 38.0 118.5 156.5 Corporate and other expenses (1) (37.5) Non-operating expenses (3.6) Net investment income 88.7 Realized and unrealized investment gains 2.5 Realized and unrealized investment losses (128.9) Realized loss on debt extinguishment — Change in fair value of loan notes issued by variable interest entities — Change in fair value of derivatives (84.9) Interest expense (9.1) Net realized and unrealized foreign exchange gains 75.2 Other income 2.9 Other expenses (8.7) Income before income taxes 53.1 Income tax (expense) (4.7) Net income $ 48.4 Net reserves for loss and loss adjustment expenses $ 1,190.4 $ 1,314.9 $ 2,505.3 Ratios Loss ratio 61.4 % 54.9 % 57.8 % Acquisition cost ratio 20.7 12.7 16.3 General and administrative expense ratio 11.6 16.1 14.1 Expense ratio 32.3 28.8 30.4 Combined ratio 93.7 % 83.7 % 88.2 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately.

Investments_2

Investments	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Income Statement Net investment income . The following table summarizes investment income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Fixed income securities — Available for sale $ 95.6 $ 87.2 $ 106.5 Fixed income securities — Trading 57.0 30.2 32.8 Short-term investments — Available for sale 0.6 0.1 0.8 Short-term investments — Trading 0.1 — 0.5 Fixed term deposits (included in cash and cash equivalents) 6.6 0.7 6.4 Catastrophe bonds — Trading 0.3 0.9 1.4 Privately-held investments — Trading 24.3 18.2 20.9 Other investments, at fair value (1) 13.9 21.9 (2.0) Total 198.4 159.2 167.3 Investment expenses (10.3) (11.7) (12.7) Net investment income $ 188.1 $ 147.5 $ 154.6 ________________ (1) Other investments represents the Company’s investments in real estate funds and other special purpose vehicles. The movement in the year represents the change in fair value of the investment and has been included as part of our investment income. The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 2.9 $ 22.7 $ 68.8 Fixed income securities — gross realized (losses) (58.4) (3.6) (1.8) Short-term investments — gross realized gains 1.0 2.0 0.5 Short-term investments — gross realized (losses) (0.5) (0.8) (0.4) Net change in expected credit (losses)/gains (5.0) (2.5) 0.4 Trading: Fixed income securities — gross realized gains 0.2 12.2 18.2 Fixed income securities — gross realized (losses) (1.8) (2.0) (3.8) Short-term investments — gross realized gains — 0.1 0.2 Short-term investments — gross realized (losses) — (0.3) (0.3) Privately-held investments — gross realized gains 0.7 0.6 — Privately-held investments — gross realized (losses) (0.1) (13.8) — Privately-held investments — net unrealized (losses)/gains (2.5) 18.1 (20.4) Catastrophe bonds — net unrealized gains/(losses) 0.2 (0.8) — Fixed income securities — net unrealized (losses) (113.9) (23.4) — Investments — equity method: Gross realized and unrealized gains/(losses) in MVI — 0.1 (0.4) Gross unrealized (losses)/gains in Multi-Line Reinsurer (0.4) 0.2 — Gross realized and unrealized (losses)/gains in Digital Risk — — (0.3) Gross realized gain on sale of Bene — — 1.8 Gross realized gain on sale of Crop Re — — 8.6 Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations $ (177.6) $ 8.8 $ 71.1 Change in available for sale net unrealized (losses)/gains: Fixed income securities (391.7) (157.6) 108.5 Income tax benefit/(expense) 23.9 (0.3) (0.5) Total change in net unrealized (losses)/gains, net of taxes recorded in other comprehensive income $ (367.8) $ (157.9) $ 108.0 Balance Sheet Fixed Income Securities and Short-Term Investments — Available For Sale. The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 __________________ (1) For the twelve months ended December 31, 2022, there was an increase in the CECL allowance on available-for-sale investments of $5.0 million (December 31, 2021 — $2.5 million decrease). As at December 31, 2021 Cost or Gross Gross Allowance Fair Market ($ in millions) U.S. government $ 1,066.2 $ 24.0 $ (5.9) $ — $ 1,084.3 U.S. agency 20.7 0.8 — — 21.5 Municipal 81.2 2.0 (0.5) (0.1) 82.6 Corporate 2,176.1 47.5 (13.0) (2.3) 2,208.3 Non-U.S. government-backed corporate 138.5 0.2 (1.9) — 136.8 Non-U.S. government 250.8 1.4 (1.2) (0.3) 250.7 Asset-backed 0.5 — — — 0.5 Non-agency commercial mortgage-backed 6.6 0.3 — — 6.9 Agency mortgage-backed 1,082.9 19.1 (12.0) — 1,090.0 Total fixed income securities — Available for sale 4,823.5 95.3 (34.5) (2.7) 4,881.6 Total short-term investments — Available for sale 10.1 — — — 10.1 Total $ 4,833.6 $ 95.3 $ (34.5) $ (2.7) $ 4,891.7 Fixed Income Securities, Short Term Investments, Equities, Catastrophe Bonds and Privately-held Investments — Trading. The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 $ 0.6 $ (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Equity securities 6.6 — — 6.6 Short-term investments 25.6 — — 25.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 As at December 31, 2021 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 115.9 $ 0.6 $ (0.2) $ 116.3 Municipal 3.9 0.1 — 4.0 Corporate 95.7 1.9 (0.8) 96.8 High yield loans 77.2 0.1 (0.4) 76.9 Non-U.S. government-backed corporate 13.3 — (0.2) 13.1 Non-U.S. government 34.9 — (0.4) 34.5 Asset-backed 784.3 3.3 (1.9) 785.7 Agency mortgage-backed 30.3 0.2 (0.3) 30.2 Total fixed income securities — Trading 1,155.5 6.2 (4.2) 1,157.5 Short-term investments — Trading 2.0 — — 2.0 Catastrophe bonds — Trading 5.3 — (1.9) 3.4 Privately-held investments — Trading Commercial mortgage loans $ 212.0 0.4 (0.9) $ 211.5 Middle market loans 66.9 — (1.5) 65.4 Asset-backed securities 26.8 — (0.2) 26.6 Equity securities 3.5 0.1 — 3.6 Total privately-held investments — Trading 309.2 0.5 (2.6) 307.1 Total Investments — Trading $ 1,472.0 $ 6.7 $ (8.7) $ 1,470.0 Catastrophe bonds. The Company has invested in catastrophe bonds with a total value of $2.9 million as at December 31, 2022 (December 31, 2021 — $3.4 million). The bonds are either zero-coupon notes or receive quarterly interest payments based on variable interest rates with scheduled maturities ranging from 2023 to 2026. The redemption value of the bonds will adjust based on the occurrence or aggregate occurrence of a covered event, such as windstorms and earthquakes in the United States, Canada, the North Atlantic, South America, Europe, Japan or Australia. Privately-held investments. The Company has invested in privately-held investments, which primarily include commercial mortgage loans of $312.1 million and middle market loans of $106.9 million as at December 31, 2022 (December 31, 2021 — commercial mortgage loans of $211.5 million; middle market loans of $65.4 million). Privately-held investments also includes investments in asset-backed securities, equity securities and other short term investments. Commercial Mortgage Loans . The commercial mortgage loans are related to investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, property type, and security to determine that properties are performing at a consistent and acceptable level to secure the related debt. The following table presents the type of commercial mortgage loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 115.3 36.9 101.6 48.1 Hotels 108.0 34.6 68.8 32.5 Office building 42.1 13.5 33.9 16.0 Other commercial 41.4 13.3 7.2 3.4 Retail 3.3 1.1 — — Industrial 2.0 0.6 — — Total commercial mortgage loans $ 312.1 100 % 211.5 100 % Geographic Region U.S. 269.8 86.4 183.7 86.9 International 42.3 13.6 27.8 13.1 Total commercial mortgage loans $ 312.1 100 % 211.5 100 % The primary credit quality indicator of commercial mortgage loans is loan performance. Non-performing commercial mortgage loans are generally 90 days or more past due. As of December 31, 2022, none of our commercial mortgage loans were non-performing. Loan-to-value and debt service coverage ratios are measures we use to assess the risk and quality of commercial mortgage loans. The loan-to-value ratio is expressed as a percentage of the value of the loan relative to the value of the underlying property. A loan-to-value ratio in excess of 100% indicates the unpaid loan amount exceeds the underlying collateral. The following table represents the loan-to-value ratio of the commercial mortgage loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 41.1 $ — 50% to 60% 248.3 131.2 61% to 70% 22.7 80.3 Commercial mortgage loans $ 312.1 $ 211.5 The debt-service coverage ratio is measured by a property’s net operating income as a multiple of its debt re-payments. A ratio of less than 1.0 reflects a property’s operations is not sufficient to cover its debt payments. The following table represents the debt-service coverage ratio of the commercial mortgage loan portfolio, excluding those that are non-performing and construction loans which are still under development, as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 106.1 $ 66.3 1.00 - 1.20x 186.1 62.4 Less than 1.00x — 18.8 Commercial mortgage loans (1) $ 292.2 $ 147.5 __________________ (1) As at December 31, 2022, we have non-performing loans of $Nil (December 31, 2021 — $Nil) and construction loans of $19.9 million (December 31, 2021 — $64.0 million) which only generate income when the construction is completed. As no income is currently being generated on these loans, they are not included in the table above. The total value of commercial mortgage loans is $312.1 million as at December 31, 2022 (December 31, 2021 — $211.5 million). Middle Market Loans. The middle market loans are investments in senior secured loan positions with full covenants, focused on the middle market in both U.S., Europe and the Caribbean. The middle market loan portfolio is diversified by industry type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, industry and security to determine that loans are performing at a consistent and acceptable level to secure the related debt. The following table presents the type of middle market loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 19.8 18.5 20.9 32.0 Financials 53.1 49.7 6.1 9.3 Industrials 18.7 17.5 18.7 28.5 Consumer discretionary 4.9 4.6 4.3 6.6 Energy 5.7 5.3 5.6 8.6 Consumer staples — — 4.9 7.5 Information technology 4.7 4.4 4.9 7.5 Total middle market mortgage loans $ 106.9 100 % $ 65.4 100 % Geographic Region U.S. 64.1 59.9 56.2 85.9 International 42.8 40.1 9.2 14.1 Total middle market loans $ 106.9 100 % $ 65.4 100 % The primary credit quality indicator of middle market loans is loan performance. Non-performing middle market loans are generally 90 days or more past due. As of December 31, 2022, all of our middle market loans were performing. Loan-to-enterprise-value and fixed charge coverage ratios are measures we use to assess the risk and quality of middle market loans. The loan-to-enterprise-value ratio is expressed as a percentage of the value of the loan relative to the value of the business. A loan-to-enterprise-value ratio in excess of 100% indicates the unpaid loan amount exceeds the value of the underlying business. The following table represents the loan-to-enterprise-value ratio of the middle market loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 63.5 $ 11.0 50% to 60% 16.4 9.2 61% to 70% 27.0 15.8 71% to 80% — 5.6 81% to 100% — 12.0 Greater than 100% — 11.8 Middle market loans $ 106.9 $ 65.4 The fixed charge coverage ratio, based upon the most recent financial statements, is expressed as a percentage of a firm’s earnings plus fixed charges to its fixed charges. Fixed charges include debt repayments, interest and equipment lease expenses. A fixed charge coverage ratio of less than 1.0 indicates a firm’s operations do not generate enough income to cover its fixed charges. The following represents the fixed charge coverage ratio of the middle market loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 95.2 $ 25.8 1.00 - 1.20x 3.8 22.8 Less than 1.00x 7.9 16.8 Middle market loans $ 106.9 $ 65.4 The Company has individually assessed each of the middle market loans with the fixed charge coverage ratio of less than 1.00x. This is mainly due to increased capital investment to support the increased business post COVID-19. These investments have been performing with the fixed charged increasing over the year. Asset-backed securities. Asset-backed securities represent interests in underlying pools of diversified referenced assets that are collateralised and backed by future cash flows and these securities are performing. Global corporate securities. The Global corporates portfolio consists of debt securities with a non-U.S. debt issuer that are backed by the cash flows generated from real estate holdings and these securities are performing. Equity securities. Equity securities consists of a single non-U.S. private issuer that is a special purpose vehicle designed to grant a first lien right to the underlying senior notes. The underlying issuer is a financial services lender to middle market companies and this security is performing. Investments — Equity Method. In January 2015, the Company, along with seven other insurance companies, established a micro-insurance venture consortium and micro-insurance incubator (“MVI”) domiciled in Bermuda. The MVI is a social impact organization that provides micro-insurance products to assist global emerging consumers. In March 2021, the Company committed an additional $0.8 million equity contribution to MVI over a 2 year period and paid $0.4 million in the period ending December 31, 2022 (December 31, 2021 — $0.4 million). On January 1, 2017, the Company purchased through its wholly-owned subsidiary, Aspen U.S. Holdings, Inc. (“Aspen U.S. Holdings”), a 49% share of Digital Risk Resources, LLC (“Digital Re”), a U.S.-based enterprise engaged in the business of developing, marketing and servicing turnkey information security and privacy liability insurance products for a total consideration of $2.3 million. The investment is accounted for under the equity method and adjustments to the carrying value of this investment are made based on the Company’s share of capital, including share of income and expenses. On December 23, 2019, the Company committed $5.0 million as an equity investment in the holding company of a multi-line reinsurer. The strategy for the multi-line reinsurer is to combine a diversified reinsurance business, focused primarily on long-tailed lines of property and casualty business and, potentially to a lesser extent, life business, with a diversified investment strategy. During the period ending December 31, 2022, $1.6 million (December 31, 2021 — $2.5 million) capital was invested in multi-line reinsurer. The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the twelve months ended December 31, 2022 and 2021: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Distribution received — — — — Unrealized (loss)/gain for the twelve months to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investment as at December 31, 2022 0.8 5.2 0.2 6.2 Opening undistributed value of investment as at January 1, 2021 $ — $ 0.5 $ 0.4 $ 0.9 Investment in the period 0.4 2.5 0.3 3.2 Distribution received — — (0.5) (0.5) Unrealized gain for the twelve months to December 31, 2021 0.1 0.2 — 0.3 Closing value of investments at December 31, 2021 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Other Investments. On December 20, 2017, the Company committed to, and during 2018 invested $100.0 million as a limited partner to a real estate fund, classified as other investments. As at December 31, 2022, the current fair value of the fund is $134.6 million (2021 — $129.9 million). On September 30, 2021, the Company committed $20.0 million as a limited partner to a third party managed real estate fund. The Partnership was established to make equity and equity related investments in multifamily and other commercial real estate properties located in the United States and its territories, with the goal of generating superior risk-adjusted returns. The Partnership seeks to acquire commercial real estate assets including real estate assets (or interests therein) that may have management or operational problems and require improvements or lack sufficient capital, including mortgage loans and development or redevelopment properties. On April 1, 2022, the Company committed an additional $10.0 million to the fund. As at December 31, 2022, the current fair value of the fund is $40.6 million (2021 — $21.4 million) and the unfunded commitment is $3.3 million. On April 1, 2022, the Company committed $30.0 million as a limited partner to a related party managed real estate fund. The Partnership was established to pursue investment opportunities to acquire, recapitalize, restructure and reposition real estate assets, portfolios and companies primarily in the United States. As at December 31, 2022, the current fair value of the fund is $25.3 million and the unfunded commitment is $5.3 million. On May 5, 2022, the Company committed $15.0 million as a limited partner to a third party managed infrastructure fund. The Partnership was established to make investments in value added infrastructure investments in environmental services, transportation, communications and digital, energy/energy transition and other infrastructure sectors primarily in North America. As at December 31, 2022, the current fair value of the fund is $8.2 million and the unfunded commitment is $8.4 million. As at December 31, 2022, the aggregate current fair value of the real estate funds investments described above is $221.3 million (2021 — $151.3 million). For further information on the real estate funds, refer to Note 20(a) in these consolidated financial statements, “Commitments and Contingencies.” Fixed income maturities, Available for sale. The scheduled maturity distribution of the Company’s available for sale fixed income securities as at December 31, 2022 and December 31, 2021 is set forth below. Actual maturities may differ from contractual maturities because issuers of securities may have the right to call or prepay obligations with or without call or prepayment penalties. As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6 At December 31, 2021 Amortized Fair Market Average ($ in millions) Due one year or less $ 545.1 $ 549.0 AA- Due after one year through five years 2,057.2 2,087.5 AA- Due after five years through ten years 1,090.5 1,106.3 A+ Due after ten years 40.7 41.4 A- Total — Government and corporate 3,733.5 3,784.2 Non-agency commercial mortgage-backed 6.6 6.9 AA+ Agency mortgage-backed 1,082.9 1,090.0 AA+ Asset-backed 0.5 0.5 AAA Total fixed income securities — Available for sale $ 4,823.5 $ 4,881.6 Guaranteed Investments. As at December 31, 2022 and December 31, 2021, the Company held no investments which are guaranteed by mono-line insurers, excluding those with explicit government guarantees. The Company’s exposure to other third-party guaranteed debt is primarily to investments backed by non-U.S. government guaranteed issuers. Gross unrealized losses, available for sale. The following tables summarize, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Company’s available for sale portfolio as at December 31, 2022 and December 31, 2021: December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166 December 31, 2021 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 309.1 $ (4.0) $ 29.3 $ (1.9) $ 338.4 $ (5.9) 51 U.S. agency 6.1 — — — 6.1 — 5 Municipal 29.7 (0.5) — — 29.7 (0.5) 20 Corporate 804.6 (11.7) 23.6 (1.3) 828.2 (13.0) 400 Non-U.S. government-backed corporate 114.4 (1.9) — — 114.4 (1.9) 10 Non-U.S. government 181.8 (1.2) 3.1 — 184.9 (1.2) 35 Agency mortgage-backed 564.5 (11.6) 16.0 (0.4) 580.5 (12.0) 116 Total fixed income securities — Available for sale 2,010.2 (30.9) 72.0 (3.6) 2,082.2 (34.5) 637 Total short-term investments — Available for sale 4.4 — — — 4.4 — 7 Total $ 2,014.6 $ (30.9) $ 72.0 $ (3.6) $ 2,086.6 $ (34.5) 644 The increase in gross unrealized losses is largely attributable to the impact of rising interest rates on our bond portfolio and mortgage-backed securities. Investments Income Statement Net investment income . The following table summarizes investment income for the six months ended June 30, 2023 and 2022; For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Fixed income securities — Available for sale $ 55.7 $ 44.5 Fixed income securities — Trading 47.8 18.9 Short-term investments — Available for sale 1.6 — Short-term investments — Trading 0.1 — Fixed term deposits (included in cash and cash equivalents) 17.3 0.5 Catastrophe bonds — Trading 1.1 0.1 Privately-held investments — Trading 21.5 8.8 Other investments, at fair value (1) (10.4) 20.7 Total 134.7 93.5 Investment expenses (5.3) (4.8) Net investment income $ 129.4 $ 88.7 __________________ (1) Other investments represents the Company’s investments in real estate, infrastructure and direct lending funds. The movement in the periods represent the change in fair value of the investment and has been included as part of our investment income. The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the six months ended June 30, 2023 and 2022: For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 0.4 $ 1.4 Fixed income securities — gross realized (losses) (6.9) (29.9) Short-term investments — gross realized (losses) (0.2) — Cash and cash equivalents — gross realized gains 0.1 0.9 Cash and cash equivalents — gross realized (losses) (0.1) (0.2) Net change in expected credit gains/(losses) 3.7 (7.7) Trading: Fixed income securities — gross realized gains 0.3 — Fixed income securities — gross realized (losses) (1.1) (0.2) Short-term investments — gross realized gains 0.1 — Short-term investments — gross realized (losses) (0.2) — Privately-held investments — gross realized gains 0.1 0.2 Privately-held investments — net unrealized (losses) (9.0) (1.3) Catastrophe bonds — net unrealized (losses) (0.6) (0.1) Fixed income securities — net unrealized gains/(losses) 31.0 (89.6) Investments — equity method: Net change in realized and unrealized gains in Multi-Line Reinsurer 0.4 0.1 Total net realized and unrealized investment gains/(losses) recorded in the consolidated statement of operations $ 18.0 $ (126.4) Change in available for sale net unrealized gains/(losses): Fixed income securities gains/(losses) 12.3 (316.0) Income tax (expense)/benefit (1.6) 29.5 Total change in net unrealized gains/(losses), net of taxes recorded in other comprehensive income $ 10.7 $ (286.5) Balance Sheet Fixed Income Securities and Short-Term Investments — Available For Sale. The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,064.9 $ — $ (51.1) $ — $ 1,013.8 U.S. agency 8.6 — (0.4) — 8.2 Municipal 159.0 — (8.8) (0.7) 149.5 Corporate 2,031.9 2.4 (155.2) (3.2) 1,875.9 Non-U.S. government-backed corporate 119.6 — (8.7) — 110.9 Non-U.S. government 281.3 — (12.0) (0.1) 269.2 Non-agency commercial mortgage-backed 6.6 — (0.9) — 5.7 Agency mortgage-backed 559.3 — (84.3) — 475.0 Total fixed income securities — Available for sale 4,231.2 2.4 (321.4) (4.0) 3,908.2 Total short-term investments — Available for sale 169.3 — — — 169.3 Total $ 4,400.5 $ 2.4 $ (321.4) $ (4.0) $ 4,077.5 __________________ (1) For the six months ended June 30, 2023, there was a decrease in the CECL allowance on available-for-sale investments of $3.7 million (December 31, 2022 — $5.0 million increase). As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 Fixed Income Securities, Short-Term Investments, Equities, Catastrophe Bonds and Privately-held Investments — Trading . The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 241.9 $ — $ (6.9) $ 235.0 Municipal 3.4 — (0.3) 3.1 Corporate 176.9 0.3 (11.8) 165.4 High yield loans 86.1 1.2 (0.7) 86.6 Non-U.S. government-backed corporate 10.1 — (0.5) 9.6 Non-U.S. government 35.8 — (1.7) 34.1 Asset-backed 975.2 1.0 (51.6) 924.6 Agency mortgage-backed 23.3 — (3.2) 20.1 Total fixed income securities — Trading 1,552.7 2.5 (76.7) 1,478.5 Short-term investments — Trading 11.0 — — 11.0 Catastrophe bonds — Trading 2.4 — — 2.4 Privately-held investments — Trading Commercial mortgage loans $ 305.5 $ 1.3 $ (11.8) $ 295.0 Middle market loans 104.1 — (2.0) 102.1 Asset-backed securities 59.5 — (1.1) 58.4 Global corporate securities 14.9 — (0.1) 14.8 Equity securities 12.1 — — 12.1 Total privately-held investments — Trading 496.1 1.3 (15.0) 482.4 Total Investments — Trading $ 2,062.2 $ 3.8 $ (91.7) $ 1,974.3 As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 0.6 (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Short-term investments 25.6 — — 25.6 Equity securities 6.6 — — 6.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 Catastrophe bonds. The Company has invested in catastrophe bonds with a total value of $2.4 million as at June 30, 2023 (December 31, 2022 — $2.9 million). The bonds are either zero-coupon notes or receive quarterly interest payments based on variable interest rates with scheduled maturities ranging from 2023 to 2026. The redemption value of the bonds will adjust based on the occurrence or aggregate occurrence of a covered event, such as windstorms and earthquakes in the United States, Canada, the North Atlantic, South America, Europe, Japan or Australia. Privately-held investments. The Company has invested in privately-held investments, which primarily include commercial mortgage loans of $295.0 million and middle market loans of $102.1 million as at June 30, 2023 (December 31, 2022 — commercial mortgage loans of $312.1 million; middle market loans of $106.9 million). Privately-held investments also includes investments in asset-backed securities, equity securities and other short-term investments. Commercial Mortgage Loans . The commercial mortgage loans are related to investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. As part of our investment process, we evaluate factors such as size, property type, and security to determine that properties are performing at a consistent and acceptable level to secure the related debt. The foll

Fair Value Measurements_2

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s estimates of fair value for financial assets and liabilities are based on the framework established in the fair value accounting guidance included in ASC Topic 820, “ Fair Value Measurements and Disclosures .” The framework prioritizes the inputs, which refer broadly to assumptions market participants would use in pricing an asset or liability, into three levels. The Company considers prices for actively traded securities to be derived based on quoted prices in an active market for identical assets, which are Level 1 inputs in the fair value hierarchy. The majority of these securities are valued using prices supplied by pricing services. The Company considers prices for other securities that may not be as actively traded which are priced via pricing services, vendors and broker-dealers, or with reference to interest rates and yield curves, to be derived based on inputs that are observable for the asset, either directly or indirectly, which are Level 2 inputs in the fair value hierarchy. The majority of these securities are also valued using prices supplied by pricing services. The Company considers securities, other financial instruments, privately-held investments and derivative insurance contracts subject to fair value measurement whose valuation is derived by internal valuation models to be based largely on unobservable inputs, which are Level 3 inputs in the fair value hierarchy. The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Asset-backed — — — — Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Held for trading financial assets, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Privately-held investments trading, at fair value — — 533.0 533.0 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 56.2 — 56.2 Liabilities under derivative contracts — foreign exchange contracts — (3.2) — (3.2) Liabilities under derivative contracts — loss portfolio transfer (2) — — (31.7) (31.7) Total 1,428.7 3,949.6 501.3 6,100.9 ________________ (1) Other investments represents our investments in real estate and other special purpose vehicles and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. At December 31, 2021 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 1,084.3 $ — $ — $ 1,084.3 U.S. agency — 21.5 — 21.5 Municipal — 82.6 — 82.6 Corporate — 2,208.3 — 2,208.3 Non-U.S. government-backed corporate — 136.8 — 136.8 Non-U.S. government 164.4 86.3 — 250.7 Asset-backed — 0.5 — 0.5 Non-agency commercial mortgage-backed — 6.9 — 6.9 Agency mortgage-backed — 1,090.0 — 1,090.0 Total fixed income securities available for sale, at fair value 1,248.7 3,632.9 — 4,881.6 Short-term investments available for sale, at fair value 6.5 3.6 — 10.1 Held for trading financial assets, at fair value U.S. government 116.3 — — 116.3 Municipal — 4.0 — 4.0 Corporate — 96.8 — 96.8 Non-U.S. government-backed corporate — 13.1 — 13.1 High yield loans — 76.9 — 76.9 Non-U.S. government 11.9 22.6 — 34.5 Asset-backed — 785.7 — 785.7 Agency mortgage-backed — 30.2 — 30.2 Total fixed income securities trading, at fair value 128.2 1,029.3 — 1,157.5 Short-term investments trading, at fair value 1.1 0.9 — 2.0 Privately-held investments — — 307.1 307.1 Catastrophe bonds trading, at fair value — 3.4 — 3.4 Other investments (1) — — — 151.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 12.9 — 12.9 Liabilities under derivative contracts — foreign exchange contracts — (13.3) — (13.3) Total $ 1,384.5 $ 4,669.7 $ 307.1 $ 6,512.6 ________________ (1) Other investments represents our investments in real estate funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” Transfers of assets into or out of a particular level are recorded at their fair values as of the end of each reporting period consistent with the date of the determination of fair value. During the twelve months ended December 31, 2022, $Nil ( December 31, 2021 — $19.5 million was transferred into Level 3) was transferred in or out of Level 3. As at December 31, 2022, there were privately-held investments carried at $533.0 million (December 31, 2021 — $307.1 million) classified as Level 3. As a result of loans sold by Aspen and loans repaid to Aspen by borrowers, a net settlement of $147.4 million occurred during the year. Additionally as at December 31, 2022, there was an embedded derivative as part of the loss portfolio transfer agreement worth $31.7 million classified as Level 3. The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Lev el 3 inputs for the twelve months ended December 31, 2022 and December 31, 2021: Twelve Months Ended December 31, 2022 Balance at beginning of year Purchases and issuances Transfers in/(out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of year Change in unrealized investment gains (losses) relating to assets held at end of year Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Liabilities under derivative contracts - loss $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Twelve Months Ended December 31, 2021 Assets Privately-held investments — trading Commercial mortgage loans $ 163.6 $ 169.9 $ — $ (122.5) $ 0.5 $ 211.5 $ (0.5) Middle market loans 112.1 5.6 — (56.1) 3.7 65.3 (1.5) Asset-backed securities 18.6 10.0 — (1.8) (0.1) 26.7 (0.2) Equity securities 5.0 0.1 — (1.6) 0.1 3.6 — Preference shares — 19.5 (19.5) — — — — Total Level 3 assets $ 299.3 $ 205.1 $ (19.5) $ (182.0) $ 4.2 $ 307.1 $ (2.2) Valuation of Fixed Income Securities . The Company’s fixed income securities are classified as either available for sale or trading and are reported at fair value. As at December 31, 2022 and December 31, 2021, the Company’s fixed income securities were valued by pricing services or broker-dealers using standard market conventions. The market conventions utilize market quotations, market transactions in comparable instruments and various relationships between instruments including, but not limited to, yield to maturity, dollar prices and spread prices in determining value. Independent Pricing Services. The underlying methodology used to determine the fair value of securities in the Company’s available for sale and trading portfolios is by the pricing services. Pricing services will gather observable pricing inputs from multiple external sources, including buy and sell-side contacts and broker-dealers, in order to develop their internal prices. Pricing services provide pricing for less complex, liquid securities based on market quotations in active markets. Pricing services supply prices for a broad range of securities including those for actively traded securities, such as Treasury and other Government securities, in addition to those that trade less frequently or where valuation includes reference to credit spreads, pay down and pre-pay features and other observable inputs. These securities include Government agency, municipals, corporate and asset-backed securities. For securities that may trade less frequently or do not trade on a listed exchange, these pricing services may use matrix pricing consisting of observable market inputs to estimate the fair value of a security. These observable market inputs include reported trades, benchmark yields, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, and industry and economic factors. Additionally, pricing services may use a valuation model such as an option adjusted spread model commonly used for estimating fair values of mortgage-backed and asset-backed securities. The Company does not derive dollar prices using an index as a pricing input for any individual security. Broker-Dealers. The Company obtains quotes from broker-dealers who are active in the corresponding markets when prices are unavailable from independent pricing services or index providers. Generally, broker-dealers value securities through their trading desks based on observable market inputs. Their pricing methodologies include mapping securities based on trade data, bids or offers, observed spreads and performance of newly issued securities. They may also establish pricing through observing secondary trading of similar securities. Quotes from broker-dealers are non-binding. The Company obtains prices for all of its fixed income investment securities via its third-party accounting service provider, and in the majority of cases receiving a number of quotes so as to obtain the most comprehensive information available to determine a security’s fair value. A single valuation is applied to each security based on the vendor hierarchy maintained by the Company’s third-party accounting service provider. As at December 31, 2022, the Company obtained an average of 2.9 quotes per fixed income investment compared to 3.0 quotes at December 31, 2021. The Company, in conjunction with its third-party accounting service provider, obtains an understanding of the methods, models and inputs used by the third-party pricing service and index providers to assess the ongoing appropriateness of vendors’ prices. The Company and its third-party accounting service provider also have controls in place to validate that amounts provided represent fair values. Processes to validate and review pricing include, but are not limited to: • quantitative analysis (e.g., comparing the quarterly return for each managed portfolio to its target benchmark, with significant differences identified and investigated); • comparison of market values obtained from pricing services and broker-dealers against alternative price sources for each security where further investigation is completed when significant differences exist for pricing of individual securities between pricing sources; • initial and ongoing evaluation of methodologies used by outside parties to calculate fair value; and • comparison of the fair value estimates to the Company’s knowledge of the current market. Prices obtained from pricing services and broker-dealers are not adjusted by us; however, prices provided by a pricing service, or broker-dealer in certain instances may be challenged based on market or information available from internal sources, including those available to the Company’s third-party investment accounting service provider. Subsequent to any challenge, revisions made by the pricing service or broker-dealer to the quotes are supplied to the Company’s investment accounting service provider. Management reviews the vendor hierarchy maintained by the Company’s third-party accounting service provider in order to determine which price source provides the most appropriate fair value (i.e., a price obtained from a pricing service with more seniority in the hierarchy will be used over a less senior one in all cases). The hierarchy level assigned to each security in the Company’s available for sale and trading portfolios is based upon its assessment of the transparency and reliability of the inputs used in the valuation as of the measurement date. The hierarchy of pricing services is determined using various qualitative and quantitative points arising from reviews of the vendors conducted by the Company’s third-party accounting service provider. Vendor reviews include annual due diligence meetings with index providers and pricing services vendors covering valuation methodology, operational walkthroughs and legal and compliance updates. Fixed Income Securities . Fixed income securities are traded on the over-the-counter (“OTC”) market based on prices provided by one or more market makers in each security. Securities such as U.S. Government, U.S. Agency, Foreign Government and investment grade corporate bonds have multiple market makers in addition to readily observable market value indicators such as expected credit spread, except for Treasury securities, over the yield curve. The Company uses a variety of pricing sources to value fixed income securities including those securities that have pay down/prepay features such as mortgage-backed securities and asset-backed securities in order to ensure fair and accurate pricing. The fair value estimates for the investment grade securities in the Company’s portfolio do not use significant unobservable inputs or modeling techniques. U.S. Government and Agency Securities. U.S. government and agency securities consist primarily of bonds issued by the U.S. Treasury and corporate debt issued by agencies such as the Federal National Mortgage Association (“FNMA”), the Federal Home Loan Mortgage Corporation (“FHLMC”) and the Federal Home Loan Bank. As the fair values of U.S. Treasury securities are based on unadjusted market prices in active markets, they are classified within Level 1. The fair values of U.S. government agency securities are priced using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of U.S. government agency securities are classified within Level 2. Municipal Securities. The Company’s municipal portfolio consist of bonds issued by U.S. domiciled state and municipality entities. The fair value of these securities is determined using spreads obtained from broker-dealers, trade prices and the new issue market which are Level 2 inputs in the fair value hierarchy. Consequently, these securities are classified within Level 2. Non-U.S. Government. The issuers for securities in this category are non-U.S. governments and their agents including, but not limited to, the U.K., Australia, Canada, France and Germany. The fair values of certain non-U.S. government bonds, primarily sourced from international indices, are based on unadjusted market prices in active markets and are therefore classified within Level 1. The remaining non-U.S. government bonds are classified within level 2 as they are not actively traded. The fair values of the non-U.S. agency securities, again primarily sourced from international indices, are priced using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of non-U.S. agency securities are classified within Level 2. In addition, foreign government securities include a portion of the Emerging Market Debt (“EMD”) portfolio which is also classified within Level 2. Corporate. Corporate securities consist primarily of short-term, medium-term and long-term debt issued by U.S. and foreign corporations covering a variety of industries and are generally priced by index providers and pricing vendors. Some issuers may participate in government programs which guarantee timely payment of principal and interest in the event of a default. The fair values of these securities are generally determined using the spread above the risk-free yield curve. Inputs used in the evaluation of these securities include credit data, interest rate data, market observations and sector news, broker-dealer quotes and trade volumes. In addition, corporate securities include a portion of the EMD portfolio. The Company classifies these securities across Level 1 and 2, with majority of them being in Level 1. Mortgage-backed Securities. Residential and commercial mortgage-backed securities consist of bonds issued by the Government National Mortgage Association, the FNMA and the FHLMC as well as private non-agency issuers. The fair values of these securities are determined through the use of a pricing model (including Option Adjusted Spread) which uses prepayment speeds and spreads to determine the appropriate average life of the mortgage-backed security. These spreads are generally obtained from broker-dealers, trade prices and the new issue market. As the significant inputs used to price mortgage-backed securities are observable market inputs, these securities are classified within Level 2. Asset-backed securities. Asset-backed securities are securities backed by notes or receivables against assets other than real estate. The underlying collateral for the Company’s asset-backed securities consists mainly of student loans, automobile loans and credit card receivables. These securities are primarily priced by index providers and pricing vendors. Inputs to the valuation process include broker-dealer quotes and other available trade information, prepayment speeds, interest rate data and credit spreads. The Company classifies these securities within Level 2. Privately-Held Investments. Privately-held investments are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models. These models include inputs that are specific to each investment. The inputs used in the fair value measurements include dividend or interest rates and appropriate discount rates. The selection of an appropriate discount rate is judgmental and is the most significant unobservable input used in the valuation of these securities. A significant increase (decrease) in this input in isolation could result in significantly lower (higher) fair value measurement for privately-held investments. In order to assess the reasonableness of the inputs the Company uses in the discounted cash flow models, the Company maintains an understanding of current market conditions, issuer specific information that may impact future cash flows as well as collaboration with independent vendors for most securities to assess the reasonableness of the discount rate being used. Commercial mortgage loans. Commercial mortgage loans consists in investments in properties including apartments, hotels, office and retail buildings, other commercial properties and industrial properties. The commercial mortgage loan portfolio is diversified by property type, geographic region and issuer to reduce risks. Commercial Mortgage Loans are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models and are classified as Level 3. Middle market loans . The middle market loans consist in investments in senior secured loan positions with full covenants, focused on the middle market in both U.S., Europe and the Caribbean. The middle market loan portfolio is diversified by industry type, geographic region and issuer to reduce risks. Middle Market Loans are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models and are classified as Level 3. Asset-backed securities . Asset-backed securities represent interests in underlying pools of diversified referenced assets that are collateralised and backed by future cash flows and these securities are performing. The fair values of these securities are determined by using discounted cash flow models and are classified as Level 3. Global corporate securities. The global corporates portfolio consists of debt securities with a non-U.S. debt issuer that are backed by the cash flows generated from real estate holdings and these securities are performing. The fair value of these securities are determined by using discounted cash flow models and are classified as Level 3. Equity securities. Equity securities consists of a single non-U.S. based issuer that is a special purpose vehicle designed to grant a first lien right to the underlying senior notes within the structure. The underlying issuer is a financial services lender to middle market companies and this security is performing. The valuation of the investments is DCF and the securities are classified as Level 3. Short-term investments. Short-term investments consist of highly liquid debt securities with a maturity greater than three months but less than one year from the date of purchase. Short-term investments are classified as either trading or available for sale according to the facts and circumstances of the investment held. Short-term investments are valued in a manner similar to the Company’s fixed maturity investments and are classified within Levels 1 and 2. The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at December 31, 2022: At December 31, 2022 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 200.7 Discounted cash flow Discount rate 3.9 % 9.4 % 5.3 % Commercial mortgage loans 85.8 Transaction Value n/a n/a n/a n/a Commercial mortgage loans 25.6 Liquidation method n/a n/a n/a n/a Middle market loans 106.9 Discounted cash flow Discount rate 7.4 % – 18.5 % 9.9 % Asset-backed securities 66.8 Discounted cash flow Discount rate 5.8 % – 9.3 % 6.7 % Global corporate securities 15.0 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Equity securities 5.3 Discounted cash flow Discount rate 9.0 % – 12.5 % 9.1 % Equity securities 1.3 Transaction Value n/a n/a n/a n/a Short-term investments 25.6 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Total $ 533.0 Catastrophe Bonds. Catastrophe bonds are variable rate fixed income instruments with redemption values adjusted based on the occurrence of a covered event, usually windstorms and earthquakes. Catastrophe bonds are classified as trading and reported at fair value. Catastrophe bonds are priced using an average of multiple broker-dealer quotes and as such, are considered Level 2. Foreign Exchange Contracts. The foreign exchange contracts which the Company uses to mitigate currency risk are characterized as OTC due to their customized nature and the fact that they do not trade on a major exchange. These instruments trade in a very deep liquid market, providing substantial price transparency and accordingly are classified as Level 2. Liabilities under derivative contracts - loss portfolio transfer. LPT embedded derivative is valued in a Black-Scholes framework. The two primary inputs of this policy are expected claim settlement patterns and expected return of the investment portfolio above a fixed minimum rate over the specified time horizon. The expected claim settlement pattern is determined on an actuarial basis for the cohort of business within scope of the LPT and is consistent with the patterns used in the valuation of technical provisions. The expected return of the investment portfolio, above a fixed minimum rate, directly impacts on the LPT derivative valuation and is subject to changes in the market conditions. In order to assess the reasonableness of the inputs, the company updates the expected claim settlement patterns on a regular basis whilst maintaining an understanding of the current market conditions. Other investments. The Company’s other investments represent our investments in real estate funds and other special purpose vehicles. Adjustments to the fair values are made based on the net asset value of the investments. The net valuation criteria established by the manager of such investments are established in accordance with the governing documents and the asset manager’s valuation guidelines, which include: the discounted cash flows method and the performance multiple approach, which uses a multiple derived from market data of comparable companies or assets to produce operating performance metrics. Alternative valuation methodologies may be employed for investments with unusual characteristics. Fair Value Measurements The Company’s estimates of fair value for financial assets and liabilities are based on the framework established in the fair value accounting guidance included in ASC Topic 820, “ Fair Value Measurements and Disclosures .” The framework prioritizes the inputs, which refer broadly to assumptions market participants would use in pricing an asset or liability, into three levels. The Company considers prices for actively traded securities to be derived based on quoted prices in an active market for identical assets, which are Level 1 inputs in the fair value hierarchy. The majority of these securities are valued using prices supplied by pricing services. The Company considers prices for other securities that may not be as actively traded which are priced via pricing services, vendors and broker-dealers, or with reference to interest rates and yield curves, to be derived based on inputs that are observable for the asset, either directly or indirectly, which are Level 2 inputs in the fair value hierarchy. The majority of these securities are also valued using prices supplied by pricing services. The Company considers securities, other financial instruments, privately-held investments and derivative insurance contracts subject to fair value measurement whose valuation is derived by internal valuation models to be based largely on unobservable inputs, which are Level 3 inputs in the fair value hierarchy. The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 1,013.8 $ — $ — $ 1,013.8 U.S. agency — 8.2 — 8.2 Municipal — 149.5 — 149.5 Corporate — 1,875.9 — 1,875.9 Non-U.S. government-backed corporate — 110.9 — 110.9 Non-U.S. government 192.7 76.5 — 269.2 Non-agency commercial mortgage-backed — 5.7 — 5.7 Agency mortgage-backed — 475.0 — 475.0 Total fixed income securities available for sale, at fair value 1,206.5 2,701.7 — 3,908.2 Short-term investments available for sale, at fair value 169.2 0.1 — 169.3 Fixed income securities, trading, at fair value 235.0 — — 235.0 Municipal — 3.1 — 3.1 Corporate — 165.4 — 165.4 Non-U.S. government-backed corporate — 9.6 — 9.6 High yield loans — 86.6 — 86.6 Non-U.S. government 12.7 21.4 — 34.1 Asset-backed — 924.6 — 924.6 Agency mortgage-backed — 20.1 — 20.1 Total fixed income securities trading, at fair value 247.7 1,230.8 — 1,478.5 Short-term investments trading, at fair value 9.1 1.9 — 11.0 Privately-held investments trading, at fair value — — 482.4 482.4 Catastrophe bonds trading, at fair value — 2.4 — 2.4 Other investments (1) — — — 213.4 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 17.2 — 17.2 Derivative liabilities — foreign exchange contracts — (13.4) — (13.4) Derivative liabilities — loss portfolio transfer (2) — — (23.4) (23.4) Total 1,632.5 3,940.7 459.0 6,245.6 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Fixed income securities, trading, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Privately-held investments — — 533.0 533.0 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 56.2 — 56.2 Derivative liabilities — foreign exchange contracts — (3.2) — (3.2) Derivative liabilities — loss portfolio transfer — — (31.7) (31.7) Total $ 1,428.7 $ 3,949.6 $ 501.3 $ 6,100.9 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictio

Reinsurance_2

Reinsurance	6 Months Ended
	Jun. 30, 2023
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The Company purchases retrocession and reinsurance to limit and diversify the Company’s risk exposure and to increase its own insurance and reinsurance underwriting capacity. These agreements provide for recovery of losses and loss adjustment expenses from reinsurers. The Company remains liable to the extent that reinsurers do not meet their obligations under these agreements. In line with its risk management objectives, the Company evaluates the financial condition of its reinsurers and monitors concentrations of credit risk. Balances pertaining to reinsurance transactions are reported “gross” on the consolidated balance sheet, meaning that reinsurance recoverable on unpaid losses and ceded unearned premiums are not deducted from insurance reserves but are recorded as assets. For more information on reinsurance recoverables, refer to Note 21, “Concentrations of Credit Risk — Reinsurance recoverables” and Note 10, “Reserves for Losses and Loss Adjustment Expenses” of these consolidated financial statements. The effect of assumed and ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the twelve months ended December 31, 2022, 2021 and 2020 was as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Premiums written: Direct $ 2,531.7 $ 2,341.4 $ 2,042.1 Assumed 1,807.0 1,597.0 1,656.4 Ceded (1,442.7) (1,350.7) (1,120.7) Net premiums written $ 2,896.0 $ 2,587.7 $ 2,577.8 Premiums earned: Direct $ 2,370.8 $ 2,139.1 $ 2,026.4 Assumed 1,617.2 1,479.2 1,612.0 Ceded (1,299.3) (1,207.8) (1,110.9) Net premiums earned $ 2,688.7 $ 2,410.5 $ 2,527.5 Insurance losses and loss adjustment expenses: Direct $ 1,574.2 $ 1,499.8 $ 1,479.6 Assumed 939.5 1,000.6 1,134.5 Ceded (833.7) (807.1) (773.3) Net insurance losses and loss adjustment expenses $ 1,680.0 $ 1,693.3 $ 1,840.8 On January 10, 2022, Aspen Holdings and certain of its subsidiaries (“Aspen”) entered into an Amended and Restated Reinsurance Agreement with a subsidiary of Enstar Group Limited (together, “Enstar”) (the “LPT”), which amended and restated the Adverse Development Cover Agreement, dated as of March 2, 2020, previously entered into between Enstar and Aspen Group (the “Original Agreement)”. Under the terms of the LPT, Enstar’s subsidiary will reinsure net losses incurred on or prior to December 31, 2019 on all of Aspen’s net loss reserves of $3,120.0 million as of September 30, 2021. The LPT provides for a limit of $3,570.0 million in consideration for a premium of $3,160.0 million. The amount of net loss reserves ceded, as well as the premium and limit amounts provided under the LPT, was adjusted for claims paid between October 1, 2021 and the closing date of the transaction. The premium includes $770 million of premium previously paid with respect to reserves ceded under the Original Agreement, which will continue to be held in trust accounts to secure the Enstar subsidiary’s obligations under the LPT. The incremental new premium will initially be held in funds withheld accounts in their original currencies maintained by Aspen but will be released to the trust accounts maintained by the Enstar subsidiary no later than September 30, 2025. The funds withheld by Aspen will be credited with interest at an annual rate of 1.75% plus, for periods after October 1, 2022, an additional amount equal to 50% of the amount by which the total return on Aspen’s investments and cash and cash equivalents exceeds 1.75%. Under the LPT, the Enstar subsidiary assumed claims control, pursuant to the provisions of an administrative services agreement subsequently entered into between the parties on June 30, 2022. Current expected loss model (“CECL”) . On June 16, 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses (Topic 326) ” which introduced a new impairment model, known as the current expected loss model (“CECL”), which is based on expected losses rather than incurred losses. Following the adoption of CECL with effect from January 1, 2020, the Company recognized a reduction in the Company’s reinsurance recoverables by $3.7 million as at December 31, 2022 (2021 — $3.3 million). For the twelve months ended December 31, 2022 there was an increase in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2021 — $0.5 million decrease). Reinsurance The Company purchases retrocession and reinsurance to limit the Company’s risk exposure and to increase its own insurance and reinsurance underwriting capacity. These agreements provide for recovery of losses and loss adjustment expenses from reinsurers. The Company remains liable to the extent that reinsurers do not meet their obligations under these agreements. In line with its risk management objectives, the Company evaluates the financial condition of its reinsurers and monitors concentrations of credit risk. Balances pertaining to reinsurance transactions are reported “gross” on the consolidated balance sheet, meaning that reinsurance recoverable on unpaid losses and ceded unearned premiums are not deducted from insurance reserves but are recorded as assets. For more information on reinsurance recoverables, refer to Note 13, “Concentrations of Credit Risk —Reinsurance recoverables” and Note 8, “Reserves for Losses and Loss Adjustment Expenses” of these unaudited condensed consolidated financial statements. The effect of ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the six months ended June 30, 2023 and 2022 was as follows: Six Months Ended June 30, 2023 2022 ($ in millions) Premiums written: Insurance $ 1,249.5 $ 1,305.7 Reinsurance 875.7 1,045.6 Ceded (774.7) (845.2) Net premiums written $ 1,350.5 $ 1,506.1 Premiums earned: Insurance $ 1,203.6 $ 1,171.5 Reinsurance 755.7 776.9 Ceded (671.9) (621.2) Net premiums earned $ 1,287.4 $ 1,327.2 Insurance losses and loss adjustment expenses: Insurance $ 691.7 $ 719.2 Reinsurance 353.4 402.4 Ceded (328.0) (353.9) Net insurance losses and loss adjustment expenses $ 717.1 $ 767.7

Derivative Contracts_2

Derivative Contracts	6 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Contracts	Derivative Contracts The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at December 31, 2022 and 2021: As at December 31, 2022 As at December 31, 2021 Derivatives Not Designated as Hedging Instruments Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivatives at Fair Value $ 945.8 $ 41.9 $ 759.8 $ 12.9 Foreign Exchange Contracts Liabilities under Derivative Contracts $ 729.5 $ (3.2) $ 785.9 $ (12.4) Loss Portfolio Transfer Liability - Embedded Derivative (2) Liabilities under Derivative Contracts — $ (31.7) — — ________________ (1) Fair value is net of $3.7 million of cash collateral (December 31, 2021 — $2.1 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. Refer to Note 7 for further information. As at December 31, 2022 As at December 31, 2021 Derivatives Designated as Hedging Instruments Under ASC 815 Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivatives at Fair Value $ 109.7 $ 14.3 $ — $ — Foreign Exchange Contracts Liabilities under Derivative Contracts $ — $ — $ 143.1 $ (0.9) The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging” for the twelve months ended December 31, 2022 and 2021: Amount of (Loss)/Gain Recognized on Derivatives For the Twelve Months Ended Location of Gain/(Loss) December 31, 2022 December 31, 2021 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives (80.5) (35.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations 5.9 (5.7) Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income 15.4 (6.2) Foreign Exchange Contracts. The Company uses foreign exchange contracts to manage foreign currency risk associated with our operating expenses but also foreign exchange risk associated with net assets or liabilities in currencies other than the U.S. dollar. A foreign exchange contract involves an obligation to purchase or sell a specified currency at a future date at a price set at the time of the contract. Foreign exchange contracts will not eliminate fluctuations in the value of the Company’s assets and liabilities denominated in foreign currencies but rather allow it to establish a rate of exchange for a future point in time. As at December 31, 2022, the Company held foreign exchange contracts that were not designated as hedges under ASC 815 with an aggregate nominal amount of $1,675.3 million (2021 — $1,545.7 million). The foreign exchange contracts are recorded as derivatives at fair value in the consolidated balance sheet with changes recorded as a change in fair value of derivatives in the consolidated statement of operations. For the twelve months ended December 31, 2022, the impact of foreign exchange contracts on net income was a loss of $80.5 million (December 31, 2021 — loss of $35.9 million). As at December 31, 2022, the Company held foreign exchange contracts that were designated as hedges under ASC 815 with an aggregate notional amount of $109.7 million (2021 — $143.1 million). The foreign exchange contracts are recorded as assets or liabilities under derivative contracts in the consolidated balance sheet with the effective portion recorded in other comprehensive income and the ineffective portion recorded as a change in fair value of derivatives in the consolidated statement of operations. The contracts are effective and therefore the movement in other comprehensive income representing the effective portion for the twelve months ended December 31, 2022 was a gain of $15.4 million (December 31, 2021 — loss of $6.2 million). As the foreign exchange contracts settle, the realized gain or loss is reclassified from other comprehensive income into general, administration and corporate expenses of the consolidated statement of operations. For the twelve months ended December 31, 2022, the amount recognized within general, administration and corporate expenses for settled foreign exchange contracts was a realized gain of $5.9 million (December 31, 2021 — loss of $5.7 million). Embedded derivative on loss portfolio contract. The loss portfolio transfer contract includes a funds withheld arrangement that provides returns to the reinsurer based on Aspen’s investment performance, guaranteeing a minimum of 1.75% return. Such funds withheld arrangements are examples of embedded derivatives and therefore this instrument is accounted for as an option-based derivative. For the twelve months ended December 31, 2022, the amount recognized as a change in fair value of derivatives in the consolidated statement of operations is $14.5 million. Derivative Contracts The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Derivatives Not Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivative assets $ 670.6 $ 7.2 $ 945.8 $ 41.9 Foreign Exchange Contracts Derivative liabilities $ 1,213.4 $ (13.4) $ 729.5 $ (3.2) Loss Portfolio Transfer Liability - Embedded Derivative (2) Derivative liabilities — $ (23.4) — (31.7) ________________ (1) Fair value is net of $2.7 million of cash collateral (December 31, 2022 — $3.7 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. As at June 30, 2023 As at December 31, 2022 Derivatives Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivative assets $ 54.7 $ 10.0 $ 109.7 $ 14.3 The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging ” for the six months ended June 30, 2023 and 2022: For the Six Months Ended Location of Gain/(Loss) June 30, 2023 June 30, 2022 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives 19.6 (84.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations (3.7) 2.8 Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income (4.3) (6.4) Foreign Exchange Contracts . The Company uses foreign exchange contracts to manage foreign currency risk associated with our operating expenses but also foreign exchange risk associated with net assets or liabilities in currencies other than the U.S. dollar. A foreign exchange contract involves an obligation to purchase or sell a specified currency at a future date at a price set at the time of the contract. Foreign exchange contracts will not eliminate fluctuations in the value of the Company’s assets and liabilities denominated in foreign currencies but rather allow it to establish a rate of exchange for a future point in time. As at June 30, 2023, the Company held foreign exchange contracts that were not designated as hedges under ASC 815 with an aggregate nominal amount of $1,884.0 million (December 31, 2022 — $1,675.3 million). The foreign exchange contracts are recorded as derivative assets or derivative liabilities in the consolidated balance sheet with changes recorded as a change in fair value of derivatives in the consolidated statement of operations. For the six months ended June 30, 2023, the impact of foreign exchange contracts on net income was a gain of $19.6 million (June 30, 2022 — loss of $84.9 million). As at June 30, 2023, the Company held foreign exchange contracts that were designated as hedges under ASC 815 with an aggregate notional amount of $54.7 million (December 31, 2022 — $109.7 million). The foreign exchange contracts are recorded as derivative assets in the consolidated balance sheet with the effective portion recorded in other comprehensive income and the ineffective portion recorded as a change in fair value of derivatives in the consolidated statement of operations. The contracts are effective and therefore the movement in other comprehensive income representing the effective portion for the six months ended June 30, 2023 was a loss of $4.3 million (June 30, 2022 — loss of $6.4 million). As the foreign exchange contracts settle, the realized gain or loss is reclassified from other comprehensive income into general, administration and corporate expenses of the consolidated statement of operations. For the six months ended June 30, 2023, the amount recognized within general, administration and corporate expenses for settled foreign exchange contracts was a realized loss of $3.7 million (June 30, 2022 — gain of $2.8 million). Embedded derivative on loss portfolio contract . The loss portfolio transfer contract includes a funds withheld arrangement that provides returns to the reinsurer based on Aspen’s investment performance, guaranteeing a minimum of 1.75% return. Such funds withheld arrangements are examples of embedded derivatives and therefore this instrument is accounted for as an option-based derivative. For the six months ended June 30, 2023, the amount recognized as a change in fair value of derivatives in the consolidated statement of operations is $8.3 million (June 30, 2022 — $Nil).

Reserves for Losses and Adjus_2

Reserves for Losses and Adjustment Expenses	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Reserves for Losses and Adjustment Expenses	Reserves for Losses and Loss Adjustment Expenses The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the twelve months ended December 31, 2022, 2021 and 2020: As at December 31, 2022 2021 2020 ($ in millions) Provision for losses and LAE at the start of the year $ 7,611.8 $ 7,165.3 $ 6,951.8 Less reinsurance recoverable (3,298.1) (3,195.2) (2,319.8) Net loss and LAE at the start of the year 4,313.7 3,970.1 4,632.0 Net loss and LAE expenses disposed (1) (1,840.1) — (818.5) Movement in net provision for losses and LAE for claims incurred: Current year 1,651.9 1,648.2 1,841.7 Prior years 28.1 45.1 (0.9) Total incurred 1,680.0 1,693.3 1,840.8 Net Losses and LAE payments for claims incurred: Current year (192.7) (729.1) (404.9) Prior years (1,098.4) (580.7) (1,359.7) Total paid (1,291.1) (1,309.8) (1,764.6) Foreign exchange (gains)/losses (49.3) (39.9) 80.4 Net losses and LAE reserves at the end of the year 2,813.2 4,313.7 3,970.1 Plus reinsurance recoverable on unpaid losses at the end of the year 4,897.7 3,298.1 3,195.2 Provision for losses and LAE at the end of the year $ 7,710.9 $ 7,611.8 $ 7,165.3 ________________ (1) Net loss and LAE expenses disposed of $1,840.1 million represent the net loss reserves as at May 20, 2022 (“Closing Date”) for losses in relation to 2019 and prior accident years, in addition to the $770.0 million of ceded reserves under the previous ADC agreement, recognizing a total recoverable of $2,610.1 million. These reserves were rolled forward from the initial effective date of September 30, 2021, at which time the net losses reserves were $3,120.0 million. As at December 31, 2022 the total amount recoverable from Enstar under the LPT was $2,132.0 million (As at December 31, 2021 recoverable from Enstar on the ADC was — $838.1 million) which includes claims paid and reserve development since the Closing Date. Net loss and LAE expenses disposed in 2020 includes the transfer of reserves under the ADC agreement providing $770.0 million of cover and the loss portfolio transfer transactions for our surety insurance book of $42.0 million and our U.S. accident and health book of $6.5 million. For the twelve months ended December 31, 2022, there was an increase of $28.1 million in the Company’s estimate of the ultimate claims to be paid in respect of prior accident years compared to an increase of $45.1 million for the twelve months ended December 31, 2021. Overall, prior year reserve strengthening totaled $28.1 million in 2022, compared with net unfavorable development of $45.1 million in 2021. Prior year reserve strengthening excludes the full economic benefit of the recoveries from the ADC of $58.3 million which is currently within reinsurance recoverables on unpaid losses. Reinsurance . Net reserve releases of $58.8 million in 2022 were mainly due to releases on prior year development on post-LPT years of $24.6 million and the favorable impact of the LPT of $34.2 million. Insurance . Net unfavorable reserve development of $86.9 million in 2022 included adverse prior year development on post-LPT years of $37.6 million and the unfavorable movement of $49.3 million due to the impact of the LPT, mainly reflecting the one-off costs in relation to the LPT recognized in 2022 and the change from ADC on a fixed allocation basis to the LPT. The following tables show an analysis of incurred claims and allocated loss adjustment expenses, net of reinsurance and cumulative paid claims and allocated claim adjustment expenses, net of reinsurance as at December 31, 2022, 2021, 2020, 2019 2018, 2017, 2016, 2015, 2014 and 2013. Under the LPT agreement, the Company has reinsured net losses incurred on all accident years 2019 and prior. This has resulted in total incurred claims, IBNR and loss adjustment expenses in the loss development triangles for 2019 and prior to be Nil. The loss development triangles are derived from all business written by the Company as although a limited number of contracts are written which have durations of greater than one year the contracts do not meet the definition of a long duration contract. All amounts included in the following tables related to transactions denominated in a foreign currency have been translated into U.S. Dollars using the exchange rates in effect at December 31, 2022. The Company has chosen to disaggregate the business in its Insurance segment, for the purposes of these loss development triangles as: Property; Casualty; Marine Aviation and Energy; and Financial and Professional insurance lines. The Company considers that this presentation of its Insurance lines loss development triangles more precisely reflects meaningful trending information. The Company presents its loss development triangles for the Reinsurance segment in line with the reportable reinsurance lines: Property Catastrophe and Other Property; Casualty; and Specialty. Property Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Accident For the Years Ended December 31, Cumulative Number of Reported Claims Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 126.7 114.4 114.2 109.9 110.9 109.0 109.3 109.5 102.1 106.1 — — 2014 162.6 154.9 132.4 133.0 132.2 130.7 130.1 125.2 131.1 — 9,949 2015 233.3 199.0 193.9 196.3 196.9 193.9 179.6 189.2 — 11,549 2016 233.9 245.0 240.0 241.3 242.5 233.4 244.8 — 10,773 2017 290.4 253.7 246.8 248.1 280.9 247.7 — 9,717 2018 196.3 198.1 182.2 196.2 177.3 — 8,308 2019 122.5 126.5 104.1 107.8 — 6,852 2020 199.9 195.9 205.1 24.4 7,542 2021 204.6 199.5 38.2 6,583 2022 163.9 62.9 4,171 Total $ 1,772.5 Property Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 37.5 73.7 86.8 98.6 103.0 105.8 107.6 107.9 106.8 106.1 2014 39.9 85.2 112.5 122.0 126.0 127.3 128.7 129.9 131.1 2015 56.3 138.3 165.1 174.1 190.1 188.9 190.4 189.2 2016 65.7 166.1 198.1 219.2 228.6 233.7 244.8 2017 95.0 185.0 217.2 237.9 242.1 247.7 2018 60.3 153.6 176.1 173.0 177.3 2019 48.0 88.6 99.3 107.8 2020 60.1 122.9 150.1 2021 58.2 118.6 2022 40.8 Total $ 1,513.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 259.0 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 259.0 Casualty Insurance Lines As at December 31, 2022 Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance Cumulative Number of Reported Claims Accident For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 128.6 112.8 111.6 116.8 99.8 101.1 101.4 100.0 107.8 86.7 — 3,392 2014 139.9 122.6 134.2 124.0 131.0 134.9 131.8 137.9 107.4 — 3,914 2015 197.9 217.9 180.5 197.5 230.1 228.3 250.4 197.2 — 4,775 2016 211.5 182.5 177.6 184.2 195.1 247.4 163.3 — 4,818 2017 176.3 169.9 173.4 190.5 234.6 154.4 — 5,495 2018 119.4 122.5 132.2 169.7 94.4 — 5,500 2019 122.0 144.4 155.3 88.3 — 5,198 2020 131.1 139.3 138.7 72.1 3,755 2021 170.5 185.6 119.7 3,356 2022 201.1 132.1 2,709 Total $ 1,417.1 Casualty Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 2.1 25.1 38.2 51.2 65.9 77.9 82.0 83.9 84.0 86.7 2014 2.5 12.6 31.5 57.3 70.1 93.1 105.4 104.0 107.4 2015 3.0 16.4 55.1 90.2 135.0 163.6 174.5 197.2 2016 4.0 22.0 38.6 79.7 106.1 128.8 163.3 2017 3.4 22.3 51.2 93.4 110.3 154.4 2018 3.0 27.2 41.4 65.5 94.4 2019 6.2 16.7 68.0 88.3 2020 — 9.2 36.1 2021 3.00 8.8 2022 23.2 Total $ 959.8 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 457.3 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 457.3 Marine, Aviation and Energy Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Cumulative Number of Reported Claims For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 319.4 332.1 340.7 324.3 331.5 345.0 343.6 338.7 346.5 319.7 — 4,179 2014 308.6 312.2 297.2 308.9 304.5 311.4 300.7 317.6 279.1 — 4,058 2015 295.3 297.0 279.3 283.7 307.2 309.9 327.3 302.7 — 4,076 2016 258.8 229.0 227.5 227.9 217.7 224.3 199.2 — 4,431 2017 209.3 199.9 206.2 213.7 231.5 205.3 — 6,059 2018 170.1 207.1 207.9 238.8 169.7 — 5,153 2019 145.5 152.8 151.1 124.0 — 3,662 2020 110.2 111.2 125.7 17.5 3,856 2021 93.0 96.1 18.3 4,863 2022 107.7 58.8 3,810 Total $ 1,929.2 Marine, Aviation and Energy Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 41.2 130.9 203.9 234.1 263.5 283.1 299.1 309.3 309.0 319.7 2014 53.2 116.0 188.1 208.6 231.3 249.5 261.7 274.2 279.1 2015 44.6 122.5 172.7 192.1 220.0 255.5 277.5 302.7 2016 30.8 81.9 141.3 163.1 189.5 197.3 199.2 2017 40.0 97.0 139.6 167.6 155.7 205.3 2018 26.7 104.3 132.6 154.7 169.7 2019 33.4 72.4 117.5 124.0 2020 28.5 66.4 88.6 2021 23.5 52.3 2022 24.9 Total $ 1,765.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 163.7 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 163.7 Financial and Professional Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 104.3 98.7 103.1 99.6 98.6 89.9 88.8 95.1 101.0 82.9 — 606 2014 133.2 128.8 127.4 117.7 128.9 118.0 118.8 124.3 118.9 — 794 2015 171.9 173.4 183.1 187.1 188.0 183.0 189.9 163.9 — 1,085 2016 188.4 209.3 213.7 199.7 182.9 189.0 163.2 — 1,244 2017 203.9 179.6 184.5 185.2 208.8 166.7 — 1,737 2018 153.7 169.4 151.2 163.2 125.4 — 4,643 2019 246.8 259.6 253.9 195.2 — 23,831 2020 346.3 346.2 336.2 118.0 105,947 2021 284.5 302.8 170.4 34,942 2022 314.8 265.2 3,487 Total $ 1,970.0 Financial and Professional Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 7.9 20.6 30.6 64.6 62.8 71.1 73.2 76.4 79.9 82.9 2014 2.8 30.2 52.7 71.1 78.5 84.0 90.9 102.3 118.9 2015 13.5 43.1 69.5 88.6 108.8 137.6 144.1 163.9 2016 14.8 70.7 100.7 128.7 124.6 133.8 163.2 2017 27.1 51.0 83.0 116.2 135.6 166.7 2018 17.4 71.6 97.8 113.3 125.4 2019 26.8 86.2 136.8 195.2 2020 47.2 120.8 174.2 2021 42.8 90.2 2022 17.5 Total $ 1,298.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 671.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 671.9 Property Catastrophe and Other Property Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 212.3 193.7 184.1 173.1 171.7 168.5 165.8 162.9 159.5 156.3 — 832 2014 185.8 172.6 157.1 145.7 145.9 141.1 141.2 140.1 138.1 — 900 2015 210.0 183.7 173.8 153.5 168.9 168.9 177.2 160.6 — 1,048 2016 264.2 264.6 263.2 242.1 237.7 230.1 229.8 — 1,307 2017 550.7 529.4 511.7 500.4 595.5 447.7 — 1,953 2018 323.5 362.8 356.0 571.0 304.5 — 1,780 2019 237.3 249.6 358.7 203.6 — 1,399 2020 317.5 402.1 348.9 81.0 1,379 2021 647.3 472.7 196.9 1,411 2022 392.3 266.7 950 Total $ 2,854.5 Property Catastrophe and Other Property Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 33.9 95.7 142.6 154.1 158.6 160.1 161.6 156.0 156.0 156.3 2014 36.9 98.5 124.4 133.7 137.4 136.0 137.6 137.8 138.1 2015 35.6 93.6 124.2 136.7 153.6 155.9 159.5 160.6 2016 55.8 160.5 200.9 211.6 224.4 230.7 229.8 2017 123.0 355.4 413.5 437.1 433.7 447.7 2018 122.1 290.1 296.8 315.3 304.5 2019 28.1 143.9 191.4 203.6 2020 41.8 165.5 237.3 2021 75.0 233.2 2022 65.5 Total $ 2,176.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 677.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 677.9 Casualty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 211.7 226.7 221.6 219.1 202.3 197.7 200.3 197.9 191.6 151.9 — 1,700 2014 201.8 204.0 212.3 205.5 199.0 202.1 198.0 191.1 144.7 — 1,843 2015 191.1 197.6 207.3 209.8 207.5 203.7 198.8 135.1 — 2,038 2016 229.3 241.4 241.0 251.0 258.5 258.5 174.6 — 2,153 2017 241.0 239.1 249.7 248.9 265.5 147.7 — 2,166 2018 226.0 255.0 262.5 264.3 130.4 — 2,002 2019 232.5 253.1 252.0 82.1 — 1,567 2020 252.6 233.6 197.9 123.2 1,088 2021 205.7 215.6 135.9 815 2022 248.7 179.1 478 Total $ 1,628.7 Casualty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 3.4 15.7 42.3 64.4 91.8 113.5 126.0 137.9 144.2 151.9 2014 2.5 13.6 37.4 59.6 85.4 105.9 123.4 133.0 144.7 2015 3.3 17.5 37.8 64.7 88.4 107.3 121.4 135.1 2016 8.9 32.9 62.9 94.8 124.6 145.3 174.6 2017 8.7 30.2 58.5 96.5 115.7 147.7 2018 7.1 33.2 73.0 103.8 130.4 2019 9.1 36.2 60.9 82.1 2020 9.1 27.6 44.1 2021 7.8 37.1 2022 9.4 Total $ 1,057.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 571.6 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 571.6 Specialty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 140.5 135.7 127.7 116.3 115.7 111.9 111.6 108.3 104.8 98.1 — 579 2014 149.5 137.5 129.5 120.8 123.6 122.2 118.0 116.6 105.4 — 622 2015 163.2 166.4 161.1 155.9 154.5 150.0 150.0 132.5 — 774 2016 235.8 236.6 234.6 227.6 222.6 218.8 197.6 — 938 2017 375.4 388.4 372.1 361.1 364.2 325.9 — 1,336 2018 392.7 391.9 390.3 419.5 342.1 — 1,403 2019 470.3 493.4 397.4 423.6 — 1,537 2020 412.8 600.0 374.1 53.1 1,470 2021 156.6 151.6 55.8 1,276 2022 193.9 107.9 969 Total $ 2,344.8 Specialty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 24.3 68.7 84.4 91.4 98.4 98.4 99.3 99.0 98.1 98.1 2014 16.2 55.2 79.8 87.8 98.0 100.9 102.5 104.4 105.4 2015 17.3 55.2 102.5 119.9 128.7 131.7 131.7 132.5 2016 58.2 149.5 163.9 181.7 191.8 201.8 197.6 2017 94.1 237.4 268.9 303.8 314.4 325.9 2018 26.7 279.0 312.2 328.5 342.1 2019 272.5 379.6 398.8 423.6 2020 212.8 269.6 290.4 2021 28.2 53.2 2022 25.8 Total $ 1,994.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 350.2 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 350.2 Reconciliation of Incurred and Paid Claims Development to total Provision for Losses and LAE Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 ($ in millions) Net outstanding liabilities: Insurance lines - Property insurance lines 259.0 289.3 - Casualty insurance lines 457.3 725.6 - Marine, aviation and energy insurance lines 163.7 427.9 - Financial and professional insurance lines 671.9 808.7 Total insurance lines 1,551.9 2,251.5 Reinsurance lines - Property catastrophe and other property reinsurance 677.9 784.9 - Casualty reinsurance 571.6 975.3 - Specialty reinsurance 350.2 472.3 Total reinsurance lines 1,599.7 2,232.5 Net loss and LAE 3,151.6 4,484.0 Reinsurance recoverable on unpaid losses: Insurance lines 2,907.8 2,117.4 Reinsurance lines 1,989.9 1,180.7 Total reinsurance recoverable on unpaid losses 4,897.7 3,298.1 Deferred gain on retroactive contracts 42.7 58.3 Unallocated claims incurred 41.4 56.6 Other reinsurance balances recoverable (1) (429.3) (286.4) Carbon syndicate reserves 5.2 1.0 Other 1.6 0.2 (338.4) (170.3) Provision for losses and LAE at the end of the year 7,710.9 7,611.8 ________________ (1) Other reinsurance balances recoverable primarily include short term recoverables to be collected. Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 Insurance 16.6 % 27.0 % 19.4 % 13.6 % 8.3 % 9.6 % 6.0 % 4.7 % 2.2 % 2.6 % Reinsurance 20.5 % 33.7 % 15.7 % 10.1 % 7.8 % 5.9 % 4.3 % 2.7 % 2.3 % 1.9 % Reserves for Losses and Loss Adjustment Expenses The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the six months at June 30, 2023 and June 30, 2022: As at June 30, As at June 30, 2023 2022 ($ in millions) Provision for losses and LAE at the start of the period $ 7,710.9 $ 7,611.8 Less reinsurance recoverable (4,897.7) (3,298.1) Net loss and LAE at the start of the period 2,813.2 4,313.7 Net loss and LAE expenses transferred (1) — (1,840.1) Movement in net provision for losses and LAE for claims incurred: Current year 723.5 775.0 Prior years (6.4) (7.3) Total incurred 717.1 767.7 Net Losses and LAE payments for claims incurred: Current year (30.8) (35.5) Prior years (438.6) (616.9) Total paid (469.4) (652.4) Foreign exchange losses/(gains) 22.0 (83.6) Net losses and LAE reserves at the end of the period 3,082.9 2,505.3 Plus reinsurance recoverable on unpaid losses at the end of the period 4,658.0 5,006.5 Provision for losses and LAE at the end of the period $ 7,740.9 $ 7,511.8 __________________ (1) Net loss and LAE expenses transferred of $1,840.1 million relates to the LPT with Enstar and represents the net loss reserves as at May 20, 2022 (“Closing Date”) for losses in relation to 2019 and prior accident years, in addition to the $770.0 million of ceded reserves under the previous ADC agreement, recognizing a total recoverable of $2,610.1 million. These reserves were rolled forward from the initial effective date of September 30, 2021, at which time the net losses reserves were $3,120.0 million. As at June 30, 2023 the total amount recoverable from Enstar under the LPT was $1,877.3 million (As at December 31, 2022 — $2,132.0 million) which includes claims paid and reserve development since the Closing Date. For the six months ended June 30, 2023, there was a reduction of $6.4 million in the Company’s estimate of the ultimate claims to be paid in respect of prior accident years compared to a reduction of $7.3 million for the six months ended June 30, 2022. Reinsurance . Net unfavorable reserve development of $2.1 million in the six months ended June 30, 2023 were mainly due to reserve strengthening in property catastrophe and reinsurance lines of business, offset by reserve releases from casualty reinsurance and specialty reinsurance. Insurance . Net reserve releases of $8.5 million in the six months ended June 30, 2023 included favorable development of $13.2 million representing the movement on the deferred gain on the LPT, offset by unfavorable development on post-LPT years of $4.7 million.

Capital Structure_2

Capital Structure	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Capital Structure	Capital Structure The following table provides a summary of the Company’s authorized and issued share capital as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2021 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2021 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 ________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. (a) Ordinary Shares Issued Ordinary Shares. The Company’s issued ordinary shares of par value $0.01 at both December 31, 2022 and 2021 was 60,395,839. The Company did not acquire any ordinary shares for the twelve months ended December 31, 2022. (b) Preference Shares Preference Shares Issuance. On May 2, 2013, the Company issued 11,000,000 5.950% Fixed-to-Floating Rate Perpetual Non-Cumulative Preference Shares, with a liquidation preference of $25 per share (the “5.950% Preference Shares”). Net proceeds were $270.6 million, consisting of $275.0 million of total liquidation preference less $4.4 million of issuance expenses. The 5.950% Preference Shares are listed on the NYSE under symbol “AHLPRC”. On September 20, 2016, the Company issued 10,000,000 shares of 5.625% Perpetual Non-Cumulative Preference Shares (the “5.625% Preference Shares”). The 5.625% Preference Shares have a liquidation preference of $25 per share. Net proceeds were $241.3 million, consisting of $250.0 million of total liquidation preference less $8.7 million of issuance expenses. The 5.625% Preference Shares are listed on the NYSE under the symbol “AHL PRD”. On August 13, 2019, the Company issued 10,000,000 depositary shares, each of which represents 1/1000 th interest in a share of the newly designated 5.625% Perpetual Non-Cumulative Preference Shares. The depositary shares have a liquidation preference of $25 per share. Net proceeds were $241.6 million, comprising $250.0 million of total liquidation preference less $8.4 million of issuance expenses. The depositary shares are listed on the NYSE under the symbol “AHL PRE”. (c) Additional Paid-in Capital Additional paid-in capital as at December 31, 2022 was $1,514.7 million (December 31, 2021 — $1,514.7 million). Included within additional paid-in capital is the aggregate liquidation preferences of the Company’s preference shares of $775.0 million less issue costs of $21.5 million (December 31, 2021 — $775.0 million less issue costs of $21.5 million). Capital Structure The following table provides a summary of the Company’s authorized and issued share capital as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2022 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2022 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 __________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. (a) Ordinary Shares Issued Ordinary Shares . The Company’s issued ordinary shares of par value $0.01 at both June 30, 2023 and December 31, 2022 was 60,395,839. The Company did not acquire any ordinary shares for the six months ended June 30, 2023. (b) Preference Shares Preference Shares Issuance . On May 2, 2013, the Company issued 11,000,000 5.950% Fixed-to-Floating Rate Perpetual Non-Cumulative Preference Shares, with a liquidation preference of $25 per share (the “5.950% Preference Shares”). Net proceeds were $270.6 million, consisting of $275.0 million of total liquidation preference less $4.4 million of issuance expenses. The first floating rate-period commenced on July 1, 2023 (payable on October 1, 2023), where the floating rate was tied to LIBOR, being 3-month LIBOR, and as contemplated by the governing instrument, 3-month LIBOR was the rate for 3-month deposits in U.S. dollars on June 29, 2023. The 5.950% Preference Shares are listed on the NYSE under symbol “AHLPRC”. On September 20, 2016, the Company issued 10,000,000 shares of 5.625% Perpetual Non-Cumulative Preference Shares (the “5.625% Preference Shares”). The 5.625% Preference Shares have a liquidation preference of $25 per share. Net proceeds were $241.3 million, consisting of $250.0 million of total liquidation preference less $8.7 million of issuance expenses. The 5.625% Preference Shares are listed on the NYSE under the symbol “AHL PRD”. On August 13, 2019, the Company issued 10,000,000 depositary shares, each of which represents 1/1000 th interest in a share of the newly designated 5.625% Perpetual Non-Cumulative Preference Shares. The depositary shares have a liquidation preference of $25 per share. Net proceeds were $241.6 million, comprising $250.0 million of total liquidation preference less $8.4 million of issuance expenses. The depositary shares are listed on the NYSE under the symbol “AHL PRE”.

Dividends_2

Dividends	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Dividends	Dividends Dividends. On March 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 April 1, 2023 March 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 April 1, 2023 March 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 April 1, 2023 March 15, 2023 ________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share. In the twelve months ended December 31, 2022, the Company paid an ordinary shares dividend of $40 million to Highlands Bermuda Holdco, Ltd., the holder of all the Company’s ordinary shares. The Company also paid an ordinary shares dividend of $20 million to Highlands Bermuda Holdco, Ltd. on April 3, 2023. Dividends Dividends . On June 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 July 1, 2023 June 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 July 1, 2023 June 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 July 1, 2023 June 15, 2023 __________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000 th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share.

Related Party Transactions_2

Related Party Transactions	6 Months Ended
	Jun. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Apollo’s indirect subsidiary, Apollo Asset Management Europe PC LLP (“AAME”), serves as the investment manager for the Company and certain of the Company’s subsidiaries, and Apollo’s indirect subsidiary, Apollo Management Holdings, L.P. (“AMH”), provides the Company with management consulting services and advisory services. Additionally, certain employees of Apollo and its affiliates serve on the Board. A description of relationships and transactions that have existed or that the Company and certain of the Company’s subsidiaries has entered into with Apollo and its affiliates are described below. Investment Management Relationships AAME provides centralized asset management investment advisory and risk services for the portfolio of the Company’s investments and investments of such subsidiaries pursuant to the investment management agreements (“IMAs”) that have been entered into with AAME. In addition, pursuant to the IMAs, AAME may engage sub-advisors or delegates to provide certain of the investment advisory and management services to the Company’s subsidiaries. Such sub-advisors may include affiliates of AAME. Under each of the IMAs, AAME will be paid an annual investment management fee (the “Management Fee”) which will be based on a cost-plus structure. The “cost” is comprised of the direct and indirect fees, costs, expenses and other liabilities arising in or otherwise connected with the services provided under the IMAs. The “plus” component will be a mark-up in an amount of up to 25% determined based on an applicable transfer pricing study. The Management Fee will be subject to certain maximum threshold levels, including an annual fee cap of 15 bps of the total amount of investable assets. Affiliated sub-advisors, including AMI and AMC, will also earn additional fees for sub-advisory services rendered. During the year ended December 31, 2022, the Company recognized IMA fees of $4.9 million (2021 — $5.8 million; 2020 — $5.3 million), of which $4.5 million (2021 — $3.2 million) remains payable to AAME at year end. Management Consulting Agreement As previously disclosed, the Company entered into a Management Consulting Agreement, dated March 28, 2019 (the “Management Consulting Agreement”), with AMH. Pursuant to the Management Consulting Agreement, AMH will provide the Company management consulting and advisory services related to the business and affairs of the Company and its subsidiaries. The Company will pay AMH in consideration for its services under the Management Consulting Agreement, an annual management consulting fee equal to the greater of (i) 1% of the consolidated net income of the Company and its subsidiaries for the applicable fiscal year, or (ii) $5 million. During the year ended December 31, 2022, the Company recognized Management Consulting fees of $5.0 million (2021 — $5.0 million; 2020 — $5.0 million), of which $1.3 million remains payable to AMH at year end (2021 — $Nil). Related Party Investments During the year, the Company bought or held the following securities or investments in Apollo: Apollo Real Estate Fund. As at December 31, 2022, the Company’s investment in Apollo Real Estate Fund had a fair value of $25.3 million. This investment is included in other investments on the consolidated balance sheet. Income earned on this investment was $1.6 million and is included in net investment income on the consolidated statement of operations and other comprehensive income. Apollo Origination Partnership (“AOP”) Fund. As at December 31, 2022, the Company’s investment in the AOP Fund had a fair value of $12.7 million. This investment is included in other investments on the consolidated balance sheet. The Company incurred gains of $1.5 million and is included in net investments income on the consolidated statement of operations and other comprehensive income. AOP Class A notes; AOP Class B notes. As at December 31, 2022, the Company’s investment in AOP Class A notes had a fair value of $30.0 million. As at December 31, 2022, the Company’s investment in AOP Class B notes had a fair value of $14.8 million. The Company incurred losses of $0.2 million and $0.2 million on AOP Class A and B notes, respectively, and is included in realized and unrealized investment losses on the consolidated statement of operations and other comprehensive income. These investments are included in privately-held investments on the consolidated balance sheet. In 2022 there were no expenses incurred relating to any of these investments. The above transactions were entered into at arm’s length. Other Payables to Related Parties Related Party Transactions Apollo’s indirect subsidiary, Apollo Asset Management Europe PC LLP (“AAME”), serves as the investment manager for the Company and certain of the Company’s subsidiaries, and Apollo’s indirect subsidiary, Apollo Management Holdings, L.P. (“AMH”), provides the Company with management consulting services and advisory services. Additionally, certain employees of Apollo and its affiliates serve on the Board. A description of relationships and transactions that have existed or that the Company and certain of the Company’s subsidiaries has entered into with Apollo and its affiliates are described below. Investment Management Relationships AAME provides centralized asset management investment advisory and risk services for the portfolio of the Company’s investments and investments of such subsidiaries pursuant to the investment management agreements (“IMAs”) that have been entered into with AAME. In addition, pursuant to the IMAs, AAME may engage sub-advisors or delegates to provide certain of the investment advisory and management services to the Company’s subsidiaries. Such sub-advisors may include affiliates of AAME. Under each of the IMAs, AAME will be paid an annual investment management fee (the “Management Fee”) which will be based on a cost-plus structure up to 25% based on an applicable transfer pricing study. The Management Fee will be subject to certain maximum threshold levels, including an annual fee cap of 15 bps of the total amount of investable assets. Affiliated sub-advisors, including AMI and AMC, will also earn additional fees for sub-advisory services rendered. During the six months ended June 30, 2023, the Company recognized IMA fees of $5.2 million (June 30, 2022 — $0.6 million), of which $2.4 million (December 31, 2022 — $4.5 million) remains payable to AAME as at June 30, 2023. Management Consulting Agreement As previously disclosed, the Company entered into a Management Consulting Agreement, dated March 28, 2019 (the “Management Consulting Agreement”), with AMH. Pursuant to the Management Consulting Agreement, AMH will provide the Company management consulting and advisory services related to the business and affairs of the Company and its subsidiaries. The Company will pay AMH in consideration for its services under the Management Consulting Agreement, an annual management consulting fee equal to the greater of (i) 1% of the consolidated net income of the Company and its subsidiaries for the applicable fiscal year, or (ii) $5 million. During the six months ended June 30, 2023, the Company recognized Management Consulting fees of $2.5 million (June 30, 2022 — $2.5 million), of which $2.5 million remains payable to AMH as at June 30, 2023 (December 31, 2022 — $1.3 million). Related Party Investments During the six months ended June 30, 2023, the Company bought or held the following securities or investments in Apollo originated and managed investments: Apollo U.S. Real Estate Fund II LP. As at June 30, 2023, the Company’s investment in Apollo U.S. Real Estate Fund II LP had a fair value of $22.9 million (December 31, 2022 — $25.3 million). This investment is included in other investments on the consolidated balance sheet. The Company incurred losses of $1.3 million (June 30, 2022 — $Nil) and is included in net investment income on the consolidated statement of operations and other comprehensive income. Apollo Origination Partnership (“AOP”) Fund. As at June 30, 2023, the Company’s investment in the AOP Fund had a fair value of $12.6 million (December 31, 2022 —$12.7 million). This investment is included in other investments on the consolidated balance sheet. The Company incurred losses of $0.4 million (June 30, 2022 — $0.2 million) and is included in net investments income on the consolidated statement of operations and other comprehensive income. AOP Class A notes; AOP Class B notes. As at June 30, 2023, the Company’s investment in AOP Class A notes had a fair value of $28.6 million (December 31, 2022 —$30.0 million). As at June 30, 2023, the Company’s investment in AOP Class B notes had a fair value of $14.0 million (December 31, 2022 —$14.8 million). The Company earned income of $1.3 million (June 30, 2022 — $0.5 million) and $0.7 million (June 30, 2022 — $0.3 million) on AOP Class A and B notes, respectively, and is included in realized and unrealized investment losses on the consolidated statement of operations and other comprehensive income. These investments are included in privately-held investments on the consolidated balance sheet. During the six months ended June 30, 2023, there were no expenses incurred relating to any of these investments (June 30, 2022 — $Nil). The above transactions were entered into at arm’s length. Other Payables to Related Parties As at June 30, 2023, the Company had an intercompany payable balance of $2.2 million (December 31, 2022 — $2.0 million), due to its parent, Highlands Bermuda Holdco, Ltd.

Commitments and Contingencies_2

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingent Liabilities (a) Restricted assets The Company’s subsidiaries are obliged by the terms of its contractual obligations to U.S. policyholders and by obligations to certain regulatory authorities to facilitate issue of letters of credit or maintain certain balances in trust funds for the benefit of policyholders. The following table details the forms and value of Company’s material restricted assets as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 707.1 $ 891.3 Third party 2,817.7 3,099.7 Letters of credit / guarantees (1) 471.3 539.8 Total restricted assets (excluding illiquid assets) 3,996.1 4,530.8 Other investments — illiquid assets 221.3 151.3 Total restricted assets and illiquid assets $ 4,217.4 $ 4,682.1 Total as percent of cash and invested assets (2) 59.4 % 59.7 % ________________ (1) As at December 31, 2022, the Company had pledged funds of $471.3 million (December 31, 2021 — $539.8 million) as collateral for the secured letters of credit. (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. Real Estate Funds. We invest in real estate funds which, as is typical for this type of investment, have lock-up periods. A lock-up period is the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. As at December 31, 2022, the lock-up periods across these funds range from one quarter to several years. Thereafter these funds could also be redeemed on a pro-rata basis depending on the liquidity position of the fund. There are no assurances as to when the Company may be able to withdraw, in whole or in part, its redemption request from the fund. Other Investments - Equity Method. On December 23, 2019, the Company committed $5.0 million as an equity investment in the holding company of a multi-line reinsurer. The strategy for the multi-line reinsurer is to combine a diversified reinsurance business, focused primarily on long-tailed lines of property and casualty business and, potentially to a lesser extent, life business, with a diversified investment strategy. During the period ending December 31, 2022, $1.6 million (December 31, 2021 — $2.5 million) capital was invested in multi-line reinsurer. The Company’s current arrangements with our bankers for the issue of letters of credit require us to provide collateral in the form of cash and investments for the full amount of all secured and undrawn letters of credit that are outstanding. We monitor the proportion of our otherwise liquid assets that are committed to trust funds or to the collateralization of letters of credit. As at December 31, 2022 and 2021, these funds amounted to approximately 59.4% of the $7.1 billion and approximately 59.7% of the $7.8 billion of investable assets held by the Company, respectively. We do not consider that this unduly restricts our liquidity at this time. For more information on our credit facilities and long-term debt arrangements, refer to Note 23, “Credit Facility and Short-term Debt” of these consolidated financial statements. Funds at Lloyd’s. AUL operates at Lloyd’s as the corporate member for Syndicate 4711. AUL also participates in underwriting activities of Carbon Syndicate 4747. Lloyd’s determines required regulatory capital by considering the underwriting activities that AUL participates in. Such capital, called Funds at Lloyd’s, consists of investable assets as at December 31, 2022 in the amount of $489.5 million (2021 — $565.8 million). The amounts provided as Funds at Lloyd’s will be drawn upon and become a liability of the Company in the event of Syndicate 4711 declaring a loss at a level that cannot be funded from other resources, or if Syndicate 4711 requires funds to cover a short-term liquidity gap. The amount which the Company provides as Funds at Lloyd’s is not available for distribution to the Company for the payment of dividends. Aspen Managing Agency Limited, the managing agent to Syndicate 4711, is also required by Lloyd’s to maintain a minimum level of capital which as at December 31, 2022 was £0.4 million (December 31, 2021 — £0.4 million). This is not available for distribution by the Company for the payment of dividends. U.S. Reinsurance Trust Fund. For its U.S. reinsurance activities, Aspen UK has established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen UK’s U.S. reinsurance liabilities, which were $1,166.4 million as at December 31, 2022 and $1,470.5 million as at December 31, 2021. As at December 31, 2022, the balance (including applicable letter of credit facilities) held in the trust was $1,389.5 million (2021 — $1,581.9 million). Aspen Bermuda has also established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen Bermuda’s liabilities to its U.S. cedants which was $380.3 million and $450.4 million as at December 31, 2022 and 2021, respectively. As at December 31, 2022, the balance held in the U.S. trust fund and other Aspen Bermuda trusts was $509.2 million (2021 — $519.7 million). U.S. Surplus Lines Trust Fund. Aspen UK and Syndicate 4711 have also established a U.S. surplus lines trust fund with a U.S. bank to secure liabilities under U.S. surplus lines policies. The balance held in trust as at December 31, 2022 was $215.1 million (2021 — $216.0 million). U.S. Regulatory Deposits. As at December 31, 2022, Aspen Specialty had a total of $6.7 million (2021 — $6.9 million) on deposit with six U.S. states in order to satisfy state regulations for writing business in those states. AAIC had a further $6.5 million (2021 — $6.4 million) on deposit with twelve U.S. states. Canadian Trust Fund. Aspen UK has established a Canadian trust fund with a Canadian bank to secure a Canadian insurance license. As at December 31, 2022, the balance held in trust was CAD$185.8 million ($137.2 million) (2021 — CAD$196.8 million). Australian Trust Fund. Aspen UK has established an Australian trust fund with an Australian bank to secure policyholder liabilities and as a condition for maintaining an Australian insurance license. As at December 31, 2022, the balance held in trust was AUD$183.9 million ($124.7 million) (2021 — AUD$226.6 million). Swiss Trust Fund. Aspen UK has established a Swiss trust fund with a Swiss bank to secure policyholder liabilities and as a condition for maintaining a Swiss insurance license. As at December 31, 2022, the balance held in trust was CHF9.4 million ($10.2 million) (2021 — CHF8.0 million). Singapore Fund. Aspen UK has established a segregated Singaporean bank account to secure policyholder liabilities and as a condition for maintaining a Singaporean insurance license and meet local solvency requirements. As at December 31, 2022, the balance in the account was SGD$174.7 million ($130.3 million) (2021 — SGD$178.0 million). (b) Contingent liabilities In common with the rest of the insurance and reinsurance industry, the Company is also subject to litigation and arbitration in the ordinary course of business. The Company’s Operating Subsidiaries are regularly engaged in the investigation, conduct and defense of disputes, or potential disputes, resulting from questions of insurance or reinsurance coverage or claims activities. Pursuant to insurance and reinsurance arrangements, many of these disputes are resolved by arbitration or other forms of alternative dispute resolution. Such legal proceedings are considered in connection with estimating the Company’s Insurance Reserves — Loss and Loss Adjustment Expenses, as provided on the Company’s consolidated balance sheet. In some jurisdictions, noticeably the U.S., a failure to deal with such disputes or potential disputes in an appropriate manner could result in an award of “bad faith” punitive damages against the Company’s Operating Subsidiaries. In accordance with ASC 450-20-50-4b, for (a) reasonably possible losses for which no accrual is made because any of the conditions for accrual in ASC 450-20-25-2 are not met and (b) reasonably possible losses in excess of the amounts accrued pursuant to ASC 450-20-30-1, the Company will provide an estimate of the possible loss or range of possible loss or state that such an estimate cannot be made. As at December 31, 2022, it was the opinion of the Company’s management based on available information that the probability of the ultimate resolution of pending or threatened litigation or arbitrations having a material effect on the Company’s financial condition, results of operations or liquidity would be remote. Commitments and Contingent Liabilities (a) Restricted assets The Company’s subsidiaries are obliged by the terms of its contractual obligations to U.S. policyholders and by obligations to certain regulatory authorities to facilitate issue of letters of credit or maintain certain balances in trust funds for the benefit of policyholders. The following table details the forms and value of Company’s material restricted assets as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 617.0 $ 707.1 Third party 2,773.8 2,817.7 Letters of credit / guarantees (1) 266.5 471.3 Total restricted assets (excluding illiquid assets) 3,657.3 3,996.1 Other investments — illiquid assets 213.4 221.3 Total restricted assets and illiquid assets $ 3,870.7 $ 4,217.4 Total as percent of cash and investable assets (2) 52.6 % 59.4 % __________________ (1) As at June 30, 2023, the Company had pledged funds as collateral for the secured letters of credit of $266.5 million (December 31, 2022 — $471.3 million). (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. The Company’s banking arrangements related to letters of credit, require the Company to provide collateral in the form of cash and securities for the full amount of all secured and undrawn letters of credit that are outstanding. The Company monitors the proportion of liquid assets that are committed to trust funds or to the collateralization of letters of credit. As at June 30, 2023 and December 31, 2022, these funds amounted to approximately 52.6% of the $7.4 billion and approximately 59.4% of the $7.1 billion of investable assets held by the Company, respectively. We do not consider that this unduly restricts our liquidity at this time. Real Estate Funds. The Company invests in real estate funds which have lock-up periods, being the initial amount of time an investor is contractually required to remain invested before having the ability to redeem. As at June 30, 2023, the lock-up periods across these funds range from one quarter to several years. Thereafter these funds may be redeemed on a pro-rata basis depending on the liquidity position of the fund. There are no assurances as to when the Company may receive, in whole or in part, its redemption request from the fund. Funds at Lloyd’s. AUL operates at Lloyd’s as the corporate member for Syndicate 4711. AUL also participates in underwriting activities of Carbon Syndicate 4747. Lloyd’s determines required regulatory capital by considering the underwriting activities of AUL, called Funds at Lloyd’s and consists of investable assets as at June 30, 2023 in the amount of $551.0 million (December 31, 2022 — $489.5 million). The Funds at Lloyd’s will be drawn upon and become a liability of the Company in the event of Syndicate 4711 declaring a loss at a level that cannot be funded from other resources, or if Syndicate 4711 requires funds to cover a short-term liquidity gap. The amount which the Company provides as Funds at Lloyd’s is not available for distribution to the Company for the payment of dividends. Aspen Managing Agency Limited, the managing agent to Syndicate 4711, is also required by Lloyd’s to maintain a minimum level of capital which as at June 30, 2023 was £0.4 million (December 31, 2022 — £0.4 million). This is not available for distribution by the Company for the payment of dividends. U.S. Reinsurance Trust Fund. For its U.S. reinsurance activities, Aspen UK has established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen UK’s U.S. reinsurance liabilities, which were $1,009.3 million as at June 30, 2023 and $1,166.4 million as at December 31, 2022. As at June 30, 2023, the balance (including applicable letter of credit facilities) held in the trust was $1,167.8 million (December 31, 2022 — $1,389.5 million). Aspen Bermuda has also established and must retain a multi-beneficiary U.S. trust fund for the benefit of its U.S. cedants so that they may take financial statement credit without the need to post cedant-specific security. The minimum trust fund amount is $20.0 million plus an amount equal to 100% of Aspen Bermuda’s liabilities to its U.S. cedants which was $306.7 million and $380.3 million as at June 30, 2023 and December 31, 2022, respectively. As at June 30, 2023, the balance held in the U.S. trust fund and other Aspen Bermuda trusts was $383.2 million (December 31, 2022 — $509.2 million). U.S. Surplus Lines Trust Fund. Aspen UK and Syndicate 4711 have also established a U.S. surplus lines trust fund with a U.S. bank to secure liabilities under U.S. surplus lines policies. The balance held in trust as at June 30, 2023 was $141.0 million (December 31, 2022 — $215.1 million). U.S. Regulatory Deposits. As at June 30, 2023, Aspen Specialty had a total of $10.3 million (December 31, 2022 — $6.7 million) on deposit with six U.S. states in order to satisfy state regulations for writing business in those states. AAIC had a further $6.7 million (December 31, 2022 — $6.5 million) on deposit with twelve U.S. states. Canadian Trust Fund. Aspen UK has established a Canadian trust fund with a Canadian bank to secure a Canadian insurance license. As at June 30, 2023, the balance held in trust was CAD$200.9 million ($151.8 million) (December 31, 2022 — CAD$185.8 million). Australian Trust Fund. Aspen UK has established an Australian trust fund with an Australian bank to secure policyholder liabilities and as a condition for maintaining an Australian insurance license. As at June 30, 2023, the balance held in trust was AUD$153.2 million ($102.0 million) (December 31, 2022 — AUD$183.9 million). Swiss Trust Fund. Aspen UK has established a Swiss trust fund with a Swiss bank to secure policyholder liabilities and as a condition for maintaining a Swiss insurance license. As at June 30, 2023, the balance held in trust was CHF$9.5 million ($10.6 million) (December 31, 2022 — CHF9.4 million). Singapore Fund. Aspen UK has established a segregated Singaporean bank account to secure policyholder liabilities and as a condition for maintaining a Singaporean insurance license and meet local solvency requirements. As at June 30, 2023, the balance in the account was SGD$172.6 million ($127.5 million) (December 31, 2022 — SGD$174.7 million). (b) Contingent liabilities In common with the rest of the insurance and reinsurance industry, the Company is also subject to litigation and arbitration in the ordinary course of business. The Company’s Operating Subsidiaries are regularly engaged in the investigation, conduct and defense of disputes, or potential disputes, resulting from questions of insurance or reinsurance coverage or claims activities. Pursuant to insurance and reinsurance arrangements, many of these disputes are resolved by arbitration or other forms of alternative dispute resolution. Such legal proceedings are considered in connection with estimating the Company’s Insurance Reserves — Loss and Loss Adjustment Expenses, as provided on the Company’s consolidated balance sheet. In some jurisdictions, noticeably the U.S., a failure to deal with such disputes or potential disputes in an appropriate manner could result in an award of “bad faith” punitive damages against the Company’s Operating Subsidiaries. In accordance with ASC 450-20-50-4b, for (a) reasonably possible losses for which no accrual is made because any of the conditions for accrual in ASC 450-20-25-2 are not met and (b) reasonably possible losses in excess of the amounts accrued pursuant to ASC 450-20-30-1, the Company will provide an estimate of the possible loss or range of possible loss or state that such an estimate cannot be made. As at June 30, 2023, it was the opinion of the Company’s management based on available information that the probability of the ultimate resolution of pending or threatened litigation or arbitrations having a material effect on the Company’s financial condition, results of operations or liquidity would be remote.

Concentration of Credit Risk_2

Concentration of Credit Risk	6 Months Ended
	Jun. 30, 2023
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	Concentrations of Credit Risk The Company is potentially exposed to concentrations of credit risk in respect of amounts recoverable from reinsurers, investments and cash and cash equivalents, and insurance and reinsurance balances owed by the brokers with whom the Company transacts business. The Company defines credit risk tolerances in line with the risk appetite set by our Board and they, together with the Group’s risk management function, monitor exposures to individual counterparties. Any exceptions are reported to senior management and the Risk Committee of the Board of Directors. Reinsurance recoverables The total amount recoverable by the Company from reinsurers as at December 31, 2022 was $4,897.7 million (2021 — $3,298.1 million) of which $2,092.4 million was uncollateralized (2021 — $1,981.4 million). As at December 31, 2022, of the Company’s uncollateralized reinsurance recoverables 9.7% (2021 — 10.8%) were with Munich Re which is rated A+ by A.M. Best and AA- by S&P, 16.3% (2021 —15.9% ) were with Everest Re which is rated A+ by A.M Best and A+ by S&P, and 8.2% (2021 — 9.3%) were with Lloyd’s which is rated A by A.M. Best and A+ by S&P. These are the Company’s largest exposures to individual reinsurers. On June 16, 2016, the FASB issued ASU 2016-13, “ Financial Instruments - Credit Losses (Topic 326) ” which introduced a new impairment model, known as the current expected loss model (“CECL”), which is based on expected losses rather than incurred losses. Under the new credit loss model, the Company would recognize an allowance for its estimate of expected credit losses and this would apply to reinsurance receivables. Following the adoption of this ASU with effect from January 1, 2020, the Company recognized a reduction in the Company’s reinsurance recoverables by $3.7 million as at December 31, 2022 (2021 — $3.3 million). For the twelve months ended December 31, 2022 there was an increase in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2021 — $0.5 million decrease). Underwriting premium receivables The total underwriting premium receivable by the Company as at December 31, 2022 was $1,482.4 million (2021 — $1,304.6 million). As at December 31, 2022, $18.3 million of the total underwriting premium receivable balance has been due for settlement for more than one year. The Company assesses the recoverability of premium receivables through a review of policies and the concentration of receivables by broker. Allowance for credit losses of $25.0 million as at December 31, 2022 (2021 — $30.2 million) for underwriting premiums unlikely to be collected. Investments and cash and cash equivalents The Company’s investment policies include specific provisions that limit the allowable holdings of a single issue and issuer. As at December 31, 2022, there were no investments in any single issuer, other than the U.S. government and the Canadian government in excess of 2% of the aggregate investment portfolio. Business through brokers The Company underwrites a significant amount of its business through brokers and a credit risk exists should any of these brokers be unable to fulfill their contractual obligations in respect of insurance or reinsurance balances due to the Company. The following table shows the largest brokers that the Company transacted business within the three years ended December 31, 2022 and the proportion of gross written premiums from each of those brokers. Twelve Months Ended December 31, 2022 2021 2020 (in percentages) Aon Corporation 22.3 % 17.3 % 15.8 % Marsh & McLennan Companies, Inc. 21.8 17.5 15.4 Willis Group Holdings, Ltd. 8.0 9.6 10.4 Other brokers/non-broker sources (1) 47.9 55.6 58.4 Total 100.0 % 100.0 % 100.0 % Gross written premiums ($ millions) $ 4,338.7 $ 3,938.4 $ 3,698.5 __________________ (1) No other individual broker accounted for more than 10% of total gross written premiums. Concentrations of Credit Risk The Company is potentially exposed to concentrations of credit risk in respect of amounts recoverable from reinsurers, investments and cash and cash equivalents, and insurance and reinsurance balances owed by the brokers with whom the Company transacts business. The Company defines credit risk tolerances in line with the risk appetite set by our Board and they, together with the Group’s risk management function, monitor exposures to individual counterparties. Any exceptions are reported to senior management and the Risk Committee of the Board of Directors. Reinsurance recoverables At June 30, 2023, the total amount recoverable by the Company from reinsurers was $4,658.0 million (December 31, 2022 — $4,897.7 million). Of the Company’s reinsurance recoverable balance at June 30, 2023, 56.0% is collateralized by our reinsurers, 43.5% is recoverable from reinsurers rated A- or higher by major rating agencies and 0.5% is recoverable from reinsurers rated lower than A- by major rating agencies (December 31, 2022 — 57.9%, 42.0% and 0.1%, respectively). As at June 30, 2023, the Company’s largest collateralized exposures to individual reinsurers represent 16.0% (December 31, 2022 —16.3%), 9.2% (December 31, 2022 — 9.7%), and 7.8% (December 31, 2022 — 8.2%). Under the current expected credit loss model (“CECL”), the Company recognized a provision against reinsurance recoverables of $3.3 million as at June 30, 2023 (December 31, 2022 — $3.7 million). For the six months ended June 30, 2023 there was a decrease in the CECL allowance on reinsurance recoverables of $0.4 million (December 31, 2022 — $0.4 million increase). Underwriting premium receivables The total underwriting premium receivable by the Company as at June 30, 2023 was $1,676.8 million (December 31, 2022 — $1,482.4 million). As at June 30, 2023, $5.9 million of the total underwriting premium receivable balance has been due for settlement for more than one year. The Company assesses the recoverability of premium receivables through a review of policies and the concentration of receivables by broker. Allowance for credit losses of $21.6 million as at June 30, 2023 (December 31, 2022 — $25.0 million) for underwriting premiums unlikely to be collected. Investments and cash and cash equivalents The Company’s investment policies include specific provisions that limit the allowable holdings of a single issue and issuer. As at June 30, 2023, there were no investments in any single issuer, other than the U.S. government and the Canadian government in excess of 2% of the aggregate investment portfolio.

Reclassifications from Accumu_2

Reclassifications from Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Reclassifications from Accumulated Other Comprehensive Income	Reclassifications from Accumulated Other Comprehensive Income The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the twelve months ended December 31, 2022 and 2021: Amount Reclassified from AOCI Details about the AOCI Components Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Affected Line Item in the ($ in millions) Available for sale: Realized (gains) on sale of securities and cash and cash equivalents $ (3.9) $ (24.8) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 58.9 4.4 Realized and unrealized investment losses 55.0 (20.4) Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 55.0 $ (20.4) Net income/(loss) Realized derivatives: Net realized gains on settled derivatives 15.4 (6.2) General, administrative and corporate expenses Tax on settled derivatives — — Income tax (expense)/benefit $ 15.4 $ (6.2) Net income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 70.4 $ (26.6) Net income/(loss) Reclassifications from Accumulated Other Comprehensive Income The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the six months ended June 30, 2023 and 2022: Amount Reclassified from AOCI Details about the AOCI Components Six Months Ended June 30, 2023 Six Months Ended June 30, 2022 Affected Line Item in the ($ in millions) Available for sale: Realized gains on sale of securities and cash and cash equivalents $ (0.4) $ (2.3) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 7.2 30.1 Realized and unrealized investment losses 6.8 27.8 Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 6.8 $ 27.8 Net income/(loss) Realized derivatives: Net realized loss on settled derivatives (4.3) (6.4) General, administrative and corporate expenses Tax on settled derivatives — 0.6 Income tax (expense)/benefit $ (4.3) $ (5.8) Net Income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 2.5 $ 22.0 Net income/(loss)

Subsequent Events_2

Subsequent Events	6 Months Ended
	Jun. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company declared and paid an ordinary shares dividend of $20 million to Highlands Bermuda Holdco, Ltd., the holder of all the Company’s ordinary shares, on April 3, 2023. Subsequent Events In July 2023, we entered into a delayed draw term loan facility for $300 million, which remains undrawn.

Basis of Preparation and Sign_3

Basis of Preparation and Significant Accounting Policies Basis of Preparation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates
Accounting for Insurance and Reinsurance Operations	Accounting for Insurance and Reinsurance Operations Premiums Earned. Premiums are recorded as written on the inception date of a policy. Premiums are recognized as revenues proportionately over the coverage period. Premiums earned are recorded in the consolidated statements of operations, net of the cost of purchased reinsurance. Premiums written which are not yet recognized as earned premium are recorded in the consolidated balance sheet as unearned premiums. Written and earned premiums and the related costs include estimates for premiums which have not been finally determined. These relate mainly to contractual provisions for the payment of adjustment or additional premiums, premiums payable under proportional treaties and delegated underwriting authorities, and reinstatement premiums. Adjustment and additional premiums are premiums charged which relate to experience during the policy term. The proportion of adjustable premiums included in the premium estimates varies between business lines with the largest adjustment premiums being in property and casualty reinsurance, marine, aviation and energy insurance and the smallest in property and casualty insurance. Premiums under proportional treaty contracts and delegated underwriting authorities are generally not reported to the Company until after the reinsurance coverage is in force. As a result, an estimate of these “pipeline” premiums is recorded. The Company estimates pipeline premiums based on projections of ultimate premium taking into account reported premiums and expected development patterns. Reinstatement premiums on assumed excess of loss reinsurance contracts are provided based on experience under such contracts. Reinstatement premiums are the premiums charged for the restoration of the reinsurance limit of an excess of loss contract to its full amount after payment by the reinsurer of losses as a result of an occurrence. The original premiums are recognized as revenue in full at the date of loss, with the reinstatement premiums recognized as revenue over the remaining cover term. Reinstatement premiums provide future insurance cover for the remainder of the initial policy term. An allowance for uncollectible premiums is established for possible non-payment of premium receivables, as deemed necessary. Credit Losses on Underwriting Premiums Receivable. Underwriting premium receivable balances are reported net of an allowance for expected credit losses. The allowance, based on ongoing review and monitoring of amounts outstanding, historical loss data, including write-offs and other relevant factors, is charged to net income in the period the receivable is recorded and revised in subsequent periods to reflect changes in the Company’s estimate of expected credit losses. Credit risk is partially mitigated by the Company’s ability to cancel the policy if the policyholder does not pay the premium. Losses and Loss Adjustment Expenses. Losses represent the amount paid or expected to be paid to claimants in respect of events that have occurred on or before the balance sheet date. The costs of investigating, resolving and processing these claims are known as loss adjustment expenses (“LAE”). The consolidated statements of operations records these losses net of reinsurance, meaning that gross losses and loss adjustment expenses incurred are reduced by the amounts recovered or expected to be recovered under reinsurance contracts. Reinsurance. Written premiums, earned premiums, incurred claims, LAE and the acquisition costs all reflect the net effect of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the Company’s acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance arises from contracts under which other insurance companies agree to share certain risks with the Company. Reinsurance accounting is followed when there is significant timing risk, significant underwriting risk and a reasonable possibility of significant loss. Outward reinsurance premiums, which are paid when the Company purchases reinsurance or retrocessional coverage, are accounted for using the same accounting methodology as the Company uses for inwards premiums. Premiums payable under reinsurance contracts that operate on a “losses occurring during” basis are expensed over the period of coverage while those arising from “risks attaching during” policies are expensed over the earnings period of the underlying premiums written from the reinsured business. Adjustment premiums and reinstatement premiums in relation to outward reinsurance are accrued when it is determined that the ultimate losses will trigger a payment and recognized within premiums payable. Reinsurance and retrocession does not isolate the ceding company from its obligations to policyholders. In the event that a reinsurer or retrocessionaire fails to meet its obligations, the ceding company’s obligations remain. Accounting for Retroactive Reinsurance Agreements. Retroactive reinsurance agreements are reinsurance agreements under which a reinsurer agrees to reimburse the Company as a result of past insurable events. For retroactive reinsurance purchased by the Company, the excess of the amounts ultimately collectible under the agreement over the consideration paid is recognized as a deferred gain liability which is amortized into income over the settlement period of the ceded reserves once the paid losses have exceeded the minimum retention. The amount of the deferral is recalculated each period based on actual loss payments and updated estimates of ultimate losses. If the consideration paid exceeds the ultimate losses collectible under the agreement, the net loss on the retroactive reinsurance agreement is recognized within income immediately. Premiums payable for retroactive reinsurance coverage and meeting the conditions of reinsurance accounting are reported as reinsurance recoverables to the extent that those amounts do not exceed recorded liabilities relating to underlying reinsurance contracts. Premiums paid in excess of accounts receivable are charged to income. Reserves. Insurance reserves are established for the total unpaid cost of claims and LAE in respect of events that have occurred by the balance sheet date, including the Company’s estimates of the total cost of claims incurred but not yet reported (“IBNR”). Claim reserves are reduced for estimated amounts of salvage and subrogation recoveries. Estimated amounts recoverable from reinsurers on unpaid losses and LAE are reflected as assets. For reported claims, reserves are established on a case-by-case basis within the parameters of coverage provided in the insurance policy or reinsurance agreement. For IBNR claims, reserves are estimated using a number of established actuarial methods to establish a range of estimates from which a management best estimate is selected. Both case and IBNR reserve estimates consider variables such as past loss experience, changes in legislative conditions, changes in judicial interpretation of legal liability, policy coverages and inflation. As many of the coverages underwritten involve claims that may not be ultimately settled for many years after they are incurred, subjective judgments as to the ultimate exposure to losses are an integral and necessary component of the loss reserving process. The Company regularly reviews its reserves, using a variety of statistical and actuarial techniques to analyze current claims costs, frequency and severity data, and prevailing economic, social and legal factors. Reserves established in prior periods are adjusted as claim experience develops and new information becomes available. Adjustments to previously estimated reserves are reflected in the financial results of the period in which the adjustments are made. The process of estimating required reserves does, by its very nature, involve considerable uncertainty. The level of uncertainty can be influenced by factors such as the existence of coverage with long duration payment patterns and changes in claims handling practices, as well as the factors noted above. Ultimate actual payments for claims and LAE could turn out to be significantly different from the Company’s estimates. Credit Losses on Reinsurance Recoverables. Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability with the reinsured business. The Company evaluates the financial condition of its reinsurers and retrocessionaires, and monitors concentration of credit risk to minimize its exposure to significant losses from individual reinsurers. To further reduce credit exposure on reinsurance recoverables, the Company has received collateral, including letters of credit and trust accounts, from certain reinsurers. Following the adoption of ASC 326, an allowance is established for expected credit losses to be recognized over the life of the reinsurance recoverable. The allowance considers the current financial strength of the individual reinsurer and the amount of collateral held. Acquisition Costs. The costs directly related to writing a (re)insurance policy are referred to as acquisition expenses and include commissions, premium taxes and profit commissions. With the exception of profit commissions, these expenses are incurred when a policy is issued, and only the costs directly related to the successful acquisition of new and renewal insurance and reinsurance contracts are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. Profit commissions are estimated and accrued based on the related performance criteria evaluated at the balance sheet date, with subsequent changes to those estimates recognized when they occur. Commissions received related to reinsurance premiums ceded are netted against broker commissions in determining acquisition costs eligible for deferral. On a regular basis a premium deficiency analysis is performed of the deferred acquisition costs in relation to the expected recognition of revenues, including anticipated investment income, and adjustments, if any, are reflected as period costs. Should the analysis indicate that the acquisition costs are unrecoverable, further analyses are performed to determine if a reserve is required to provide for losses which may exceed the related unearned premium. General and Administrative Expenses. These costs represent the expenses incurred in running the business and include, but are not limited to compensation costs for employees, rental costs, IT development and professional and consultancy fees. General and administrative costs directly attributable to the successful acquisition of business are deferred and amortized over the same period as the corresponding premiums are recorded as revenues. When reporting the results for its business segments, the Company includes expenses which are directly attributable to the segment plus an allocation of central administrative costs. Corporate Expenses.
Accounting for Investments, Cash and Cash Equivalents	Accounting for Investments, Cash and Cash Equivalents Fixed Income Securities. The fixed income securities portfolio comprises securities issued by governments and government agencies, corporate bonds, mortgage and other asset-backed securities and bank loans. Investments in fixed income securities are classified as available for sale or trading and are reported at estimated fair value in the consolidated balance sheet. Investment transactions are recorded on the trade date with balances pending settlement reflected in the consolidated balance sheet under receivables for securities sold and other payables for securities purchased, respectively. Fair values are based on quoted market prices and other data provided by third-party pricing services. Short-term Investments. Short-term investments primarily comprise highly liquid debt securities with a maturity greater than three months but less than one year from the date of purchase and are held as part of the investment portfolio of the Company. Short-term investments are classified as either trading or available for sale and reported at estimated fair value. Catastrophe Bonds. Investments in catastrophe bonds are classified as trading and are reported on the consolidated balance sheet at estimated fair value. The fair values are based on independent broker-dealer quotes. Privately-held Investments. The Company’s privately-held investments primarily comprise commercial mortgage loans, middle market loans, asset-backed securities, global corporate securities and equity securities. These investments are classified as trading and are reported on the consolidated balance sheet at estimated fair value. Privately-held investments are initially valued at cost or transaction value which approximates fair value. In subsequent measurement periods, the fair values of these securities are primarily determined using internally developed discounted cash flow models. Interest income is accrued on the principal amount of the loan based on its contractual interest rate subject to it being probable that we will receive interest on that particular underlying loan. Interest income, amortization of premiums and discounts, and prepayment fees are reported in net investment income on the consolidated statements of income. Other Investments, Equity Method. Other investments represent the Company’s investments that are recorded using the equity method of accounting. Adjustments to the fair value of these investments are made based on the net asset value of the investment. Other Investments. Other investments represent the Company’s investments in real estate funds and other special purpose vehicles. Adjustments to the fair value are made based on the net asset value of the investment. Cash and Cash Equivalents. Cash and cash equivalents are reported at fair value. Cash and cash equivalents comprise cash on hand, deposits held on call with banks and other short-term highly liquid investments due to mature within three months from the date of purchase and which are subject to insignificant risk of change in fair value. Gains and Losses. Realized gains or losses on the sale of investments are determined on the basis of the first in first out cost method and are recorded in revenue or expenses respectively. Unrealized gains and losses represent the difference between the cost, or the cost as adjusted by amortization of any difference between its cost and its redemption value (“amortized cost”), of the security and its fair value at the reporting date and are included within other comprehensive income for securities classified as available for sale and in realized and unrealized investment gains or losses in the consolidated statement of operations for securities classified as trading. Credit Losses on Available for Sale Debt Securities . Following Aspen’s adoption of ASU 2016-13 “Financial Instruments - Credit Losses (Topic 326)” , effective January 1, 2020, current expected credit losses (CECL) are recognized through an allowance account for available for sale debt securities, thereby permitting reversals of previously recognized credit losses through net income in the period they occur. Write-offs (of any previously recognized allowance for credit losses) are recorded when amounts are deemed uncollectible, or Aspen intends to sell (or more likely than not will be required to sell) the debt security before recovery of the amortized cost basis. The amortized cost basis will be written down to the debt securities fair value through earnings. Credit losses are limited to the difference between the debt securities amortized cost basis and fair value (‘fair-value floor’). Any decline in the debt securities fair value below the amortized cost basis that is not a result of a credit loss is recorded through other comprehensive income, net of applicable taxes. Our credit loss models employ a discounted cash flow approach to evaluate whether a credit loss exists at the individual security level and are reviewed at each reporting period. This analysis excludes investments in U.S. Government / Agency bonds and U.S. Government Agency mortgage-backed securities due to being of ‘high credit quality’ based on the absence of risk. Available for sale debt securities that were initially purchased with credit deterioration (PCD), the amortized cost basis shall be considered to be the purchase price, plus any allowance for credit losses. Estimated credit losses shall be discounted at the rate that equates the present value of the purchaser’s estimate of the security’s future cash flows with the purchase price of the asset. Holding gains or losses are recognition through other comprehensive income, net of applicable taxes. No changes in the estimate of credit losses have taken place during the period. Net Investment Income.
Accounting for Derivative Financial Instruments	Accounting for Derivative Financial Instruments The Company enters into derivative instruments such as interest rate swaps and forward exchange contracts in order to manage certain market and credit risks. The Company records derivative instruments at fair value on the Company’s consolidated balance sheet as either assets or liabilities, depending on their rights and obligations. The accounting for the gain or loss due to the changes in the fair value of these instruments is dependent on whether the derivative qualifies as a hedge. If the derivative does not qualify as a hedge, the gains or losses are reported in the consolidated statement of operations when they occur. If the derivative qualifies as a hedge, the accounting treatment varies based on the type of risk being hedged. Gains and losses on the effective portion of such contracts are recognized in other comprehensive income. As the contracts settle, the realized gain or loss is reclassified from other comprehensive income into the consolidated statement of operations. The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangements is considered an embedded derivative and accounted for as an option-based derivative. Since the economic characteristics and risks of an embedded derivative feature are not clearly and closely related to the economic characteristics and risks of the host contract, the embedded derivative is bifurcated and accounted for separately at fair value. The Company records subsequent changes in the embedded derivative fair value in the consolidated statement of operations.
Accounting for Intangible Assets	Accounting for Intangible Assets Intangible assets are held in the consolidated balance sheet at cost less amortization and impairment. Amortization applies on a straight-line basis in respect of assets having a finite estimated useful economic life. Finite intangibles are assessed on an annual basis for impairment, or more frequently where circumstances indicate the carrying value may not be recoverable. For intangible assets considered to have an indefinite life, the Company performs a qualitative assessment annually to determine whether it is more likely than not that an intangible asset is impaired. Goodwill is assessed annually for impairment or more frequently if circumstances indicate an impairment may have occurred.
Accounting for Office Properties and Equipment	Accounting for Office Properties and Equipment Office properties and equipment are reported at cost less accumulated depreciation. These assets are depreciated on a straight-line basis over the estimated useful lives of the assets. Computer equipment is depreciated between three IT development costs that are directly associated with the development of identifiable and unique software products and that are anticipated to generate economic benefits exceeding costs beyond one year, are recognized within office properties and equipment. Costs include external consultants’ fees, certain qualifying internal staff costs and other costs incurred to develop software programs. Software is depreciated over their estimated useful life, between three and five years, on a straight-line basis and is subject to impairment testing annually. Depreciation commences when the asset becomes operational. Other non-qualifying costs are expensed as incurred.
Accounting for Right-of-Use Operating Lease Assets	Accounting for Leases In the ordinary course of the business, the Company renews and enters into new leases for office real estate and other assets. At the lease inception date, the Company determines whether a contract contains a lease and recognizes operating lease Right-of-use assets and operating lease liabilities based on the present value of future minimum lease payments. As our leases do not provide an implicit interest rate, we use our incremental borrowing rate based on the information available at the commencement date to determine the present value of future payments. For all office real estate leases, rent incentives, including reduced-rent and rent free periods and contractually agreed rent increases during the lease term, have been included when determining the present value of future cash flows. Right-of-use operating lease assets are reported at cost less accumulated depreciation on the consolidated balance sheet and depreciated over the lease term. The Company does not record office property and equipment leases with an initial term of 12 months or less (short-term) in the Company's consolidated balance sheets. Such short-term leases are expensed through the consolidated statement of operations.
Accounting for Foreign Currencies Translation	Accounting for Foreign Currencies Translation The reporting currency of the Company is the U.S. Dollar. Effective January 1, 2022, management reassessed its functional currency determination in accordance with ASC 830, Foreign Currency Matters, as a result of significant changes in the Group’s economic facts and circumstances, and concluded that the functional currency of certain of its foreign operations had changed. Consequently, the Company has concluded that the U.S. Dollar is now the functional currency for all its branches and overseas entities. The change in the Company’s functional currency determination has been applied on a prospective basis in accordance with ASC 830. Therefore, any translation gains and losses that were previously recorded in accumulated other comprehensive income through December 31, 2021 remain unchanged through December 31, 2021. From January 1, 2022, any net realized and unrealized gains/(losses) on translation are recognized in the consolidated statements of operations and other comprehensive income (loss). Investments classified as available-for-sale are recorded at fair value, the portion attributable to movements in exchange rates continues to be included within accumulated other comprehensive income. Transactions in currencies other than the functional currency are measured at the exchange rate prevailing at the date of the transaction. Monetary assets and liabilities denominated in non-functional currencies are remeasured at the exchange rate prevailing at the balance sheet date and any resulting foreign exchange gains or losses are reflected in the consolidated statement of operations. Non-monetary assets and liabilities are remeasured to functional currency at historic exchange rates.
Accounting for Income Tax	Accounting for Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. When the Company does not believe that, on the basis of available information, it is more likely than not that deferred tax assets will be fully recovered, it recognizes a valuation allowance against its deferred tax assets to reduce the deferred tax assets to the amount more likely than not to be realized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Furthermore, a tax benefit from a tax position may be recognized in the financial statements only if it is more-likely-than-not that the position is sustainable, based solely on its technical merits and consideration of the relevant tax authority’s widely understood administrative practices and precedents. The Company applies a portfolio approach to release the income tax effects in accumulated other comprehensive income. Under this approach, the income tax effects upon the sale of an available-for-sale debt security, settlement of hedged transactions and upon foreign currency translation adjustments for each period, are determined under the intraperiod tax allocation approach. Any tax effects remaining in accumulated other comprehensive income are only released when the entire portfolio is liquidated, sold or extinguished.
Accounting for Preference Shares	Accounting for Preference Shares
Accounting for Long-term Incentive Plans	Accounting for Long-Term Incentive Plans The Company operates an employee long-term incentive plan, comprised of Performance Units and Exit Units, the terms and conditions of which are described in Note 16. The Company applies a fair-value based measurement method in calculating the compensation costs of Performance Units which are recognized on a straight-line basis over the vesting period.
Accounting for Business Combinations	Accounting for Business Combinations The Company accounts for a transaction as a business combination where the assets acquired and liabilities assumed following a transaction constitute a business. An acquired entity must have inputs and processes that make it capable of generating a return or economic benefit to be considered a business. If the assets acquired are not a business, the Company accounts the transaction as an asset acquisition. The Company recognizes and measures at fair value 100 percent of the assets and liabilities of any acquired business. Goodwill is recognized and measured as the difference between the consideration paid or payable less the fair value of assets acquired. The Company accounts for the disposal of subsidiary undertakings when it ceases to control the subsidiary’s assets and liabilities or the group of assets. A gain or loss is recognized and measured as the difference between the fair value of consideration received or receivable and the value of assets, liabilities and equity components de-recognized, related to that subsidiary or group of assets when deconsolidated. Costs that are directly related to a business combination transaction are expensed in the periods in which the costs are incurred and the services are received.
Accounting Pronouncements	Accounting Pronouncements Accounting Pronouncements Adopted In March 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326 )”. This update is as a result of a post implementation review done on the issued ASU No.2016-13 , Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , addressing “troubled debt restructuring by creditors” and “vintage disclosures”. This update will be effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Accounting Pronouncements Not Yet Adopted In March 2022, the FASB issued Accounting Standards Update No. ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging, Portfolio Layer Method ”. This update addresses concerns from entities and practitioners regarding the ‘last-of-layer’ method of accounting incorporated in update No. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” , issued on 28 August, 2017. This method is meant to achieve fair value hedge accounting for interest rate risk hedges of portfolios of ‘prepayable financial assets’. This ASU will be effective for fiscal years beginning after December 15, 2023 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In June 2022, the FASB issued Accounting Standards Update No. ASU 2022-03, “Fair Value Measurement (Topic 820 )”. This update is for entities that have investments in equity securities, measured at fair value, which are subject to a contractual sale restriction. This update will be effective for fiscal years beginning after December 15, 2024 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In September 2022, the FASB issued Accounting Standards Update No. ASU 2022-04, “Liabilities- Supplier Finance Programs (Subtopic 405-50)” . The update has been issued to enhance the transparency of supplier finance program disclosure for all entities that use these programs in connection with the purchase of goods and services. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that the update has no impact, as the Company does not enter into any such agreement. In December 2022, the FASB issued Accounting Standards Update No. ASU 2022-05 , “Financial Services- Insurance (Topic 944 )”. This update reduces the implementation costs and complexity with the adoption of Long Duration Insurance contracts (LDTI) that have been derecognized in accordance with the amendments in this update. These changes eliminate the need to reclassify a portion of previously recognized gains or losses to the LDTI transition adjustment as suggested in the previous ASU issued 2020-11. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that the update has no impact, as the Company does not write long-duration business. In December 2022, the FASB issued Accounting Standards Update No. ASU 2022-06, “Reference Rate Reform (Topic 848)”. This update defers the sunset date of Topic 848 (ASU 2020-04) from Dec 31, 2022 to Dec 31, 2024, after which entities will no longer be allowed to use the relief offered in Topic 848. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Other accounting pronouncements were issued during the year ended December 31, 2022 which were either not applicable to the Company or did not impact the Company’s consolidated financial statements. Accounting Pronouncements Adopted in 2023 In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2017-04, Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Among other things, ASU 2017-04 requires the following: (1) the elimination of step two of the goodwill impairment test; entities will no longer utilize the implied fair value of their assets and liabilities for purposes of testing goodwill for impairment, and (2) the quantitative portion of the goodwill impairment test will be performed by comparing the fair value of a reporting unit with its carrying amount; an impairment charge is to be recognized for the excess of carrying amount over fair value, but only to the extent of the amount of goodwill allocated to that reporting unit. The effective date for this ASU was amended via ASU 2019-10, Effective Dates, and became effective for annual periods beginning after December 15, 2022. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements.

Basis of Preparation and Sign_4

Basis of Preparation and Significant Accounting Policies Basis of Preparation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Accounting Pronouncements	Accounting Pronouncements Accounting Pronouncements Adopted In March 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326 )”. This update is as a result of a post implementation review done on the issued ASU No.2016-13 , Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , addressing “troubled debt restructuring by creditors” and “vintage disclosures”. This update will be effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Accounting Pronouncements Not Yet Adopted In March 2022, the FASB issued Accounting Standards Update No. ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging, Portfolio Layer Method ”. This update addresses concerns from entities and practitioners regarding the ‘last-of-layer’ method of accounting incorporated in update No. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” , issued on 28 August, 2017. This method is meant to achieve fair value hedge accounting for interest rate risk hedges of portfolios of ‘prepayable financial assets’. This ASU will be effective for fiscal years beginning after December 15, 2023 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In June 2022, the FASB issued Accounting Standards Update No. ASU 2022-03, “Fair Value Measurement (Topic 820 )”. This update is for entities that have investments in equity securities, measured at fair value, which are subject to a contractual sale restriction. This update will be effective for fiscal years beginning after December 15, 2024 and interim periods within those fiscal years. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. In September 2022, the FASB issued Accounting Standards Update No. ASU 2022-04, “Liabilities- Supplier Finance Programs (Subtopic 405-50)” . The update has been issued to enhance the transparency of supplier finance program disclosure for all entities that use these programs in connection with the purchase of goods and services. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that the update has no impact, as the Company does not enter into any such agreement. In December 2022, the FASB issued Accounting Standards Update No. ASU 2022-05 , “Financial Services- Insurance (Topic 944 )”. This update reduces the implementation costs and complexity with the adoption of Long Duration Insurance contracts (LDTI) that have been derecognized in accordance with the amendments in this update. These changes eliminate the need to reclassify a portion of previously recognized gains or losses to the LDTI transition adjustment as suggested in the previous ASU issued 2020-11. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that the update has no impact, as the Company does not write long-duration business. In December 2022, the FASB issued Accounting Standards Update No. ASU 2022-06, “Reference Rate Reform (Topic 848)”. This update defers the sunset date of Topic 848 (ASU 2020-04) from Dec 31, 2022 to Dec 31, 2024, after which entities will no longer be allowed to use the relief offered in Topic 848. During the year, the Company evaluated and considered the provisions of this ASU update and has concluded that there is no material impact on the consolidated financial statements for the current financial year. Other accounting pronouncements were issued during the year ended December 31, 2022 which were either not applicable to the Company or did not impact the Company’s consolidated financial statements. Accounting Pronouncements Adopted in 2023 In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2017-04, Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Among other things, ASU 2017-04 requires the following: (1) the elimination of step two of the goodwill impairment test; entities will no longer utilize the implied fair value of their assets and liabilities for purposes of testing goodwill for impairment, and (2) the quantitative portion of the goodwill impairment test will be performed by comparing the fair value of a reporting unit with its carrying amount; an impairment charge is to be recognized for the excess of carrying amount over fair value, but only to the extent of the amount of goodwill allocated to that reporting unit. The effective date for this ASU was amended via ASU 2019-10, Effective Dates, and became effective for annual periods beginning after December 15, 2022. The adoption of this ASU did not have a material impact on the Company’s consolidated financial statements.

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Summary of gross and net written and earned premiums, underwriting results, ratios and reserves for each of Company's business segments	The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for the twelve months ended December 31, 2022, 2021 and 2020: Twelve Months Ended December 31, 2022 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,807.0 $ 2,531.7 $ 4,338.7 Net written premiums 1,426.4 1,469.6 2,896.0 Gross earned premiums 1,617.2 2,370.8 3,988.0 Net earned premiums 1,251.8 1,436.9 2,688.7 Underwriting Expenses Losses and loss adjustment expenses 770.3 909.7 1,680.0 Acquisition costs 252.4 179.4 431.8 General and administrative expenses 142.5 244.0 386.5 Underwriting income 86.6 103.8 190.4 Corporate expenses (71.7) Non-operating expenses (1) (36.0) Net investment income 188.1 Realized and unrealized investment gains 5.0 Realized and unrealized investment losses (182.6) Change in fair value of derivatives (80.5) Interest expense (43.7) Net realized and unrealized foreign exchange gains 15.9 Other income 8.2 Other expenses (20.1) (Loss) before income taxes (27.0) Income tax benefit 78.1 Net income $ 51.1 Net reserves for loss and loss adjustment expenses $ 1,360.7 $ 1,452.5 $ 2,813.2 Ratios Loss ratio 61.5 % 63.3 % 62.5 % Acquisition cost ratio 20.2 12.5 16.1 General and administrative expense ratio 11.4 17.0 14.4 Expense ratio 31.6 29.5 30.5 Combined ratio 93.1 % 92.8 % 93.0 % ________________ (1) Non-operating expenses includes $32.7 million in relation to fixed assets written off, $10.0 million of severance, consulting and professional services in relation to non-recurring projects and other costs, offset by $6.7 million of write backs related to leased office space. Twelve Months Ended December 31, 2021 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,597.0 $ 2,341.4 $ 3,938.4 Net written premiums 1,199.0 1,388.7 2,587.7 Gross earned premiums 1,479.2 2,139.1 3,618.3 Net earned premiums 1,118.8 1,291.7 2,410.5 Underwriting Expenses Losses and loss adjustment expenses 705.2 988.1 1,693.3 Acquisition costs 221.6 192.5 414.1 General and administrative expenses 121.3 211.8 333.1 Underwriting income/(loss) 70.7 (100.7) (30.0) Corporate expenses (64.3) Non-operating expenses (1) (20.6) Net investment income 147.5 Realized and unrealized investment gains 56.2 Realized and unrealized investment losses (47.4) Change in fair value of derivatives (35.9) Interest expense (14.3) Net realized and unrealized foreign exchange gains 40.0 Other income 14.7 Other expenses (10.8) Income before income taxes 35.1 Income tax (expense) (5.3) Net income $ 29.8 Net reserves for loss and loss adjustment expenses $ 2,148.4 $ 2,165.3 $ 4,313.7 Ratios Loss ratio 63.0 % 76.5 % 70.2 % Acquisition cost ratio 19.8 14.9 17.2 General and administrative expense ratio 10.8 16.4 13.8 Expense ratio 30.6 31.3 31.0 Combined ratio 93.6 % 107.8 % 101.2 % ________________ (1) Non-operating expenses includes $19.3 million of costs related to consulting and professional services in relation to non-recurring projects and other costs, $0.4 million of impairment charges related to lease assets as a result of exiting certain office space and $0.9 million of amortization of intangible assets and other non-operating expenses. Twelve Months Ended December 31, 2020 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,656.4 $ 2,042.1 $ 3,698.5 Net written premiums 1,297.7 1,280.1 2,577.8 Gross earned premiums 1,612.0 2,026.4 3,638.4 Net earned premiums 1,287.7 1,239.8 2,527.5 Underwriting Expenses Losses and loss adjustment expenses 958.6 882.2 1,840.8 Acquisition costs 246.0 219.7 465.7 General and administrative expenses 110.8 197.2 308.0 Underwriting (loss) (27.7) (59.3) (87.0) Corporate expenses (70.2) Non-operating expenses (1) (32.7) Net investment income 154.6 Realized and unrealized investment gains 98.5 Realized and unrealized investment losses (27.4) Change in fair value of derivatives (65.1) Interest expense (33.9) Net realized and unrealized foreign exchange (losses) (13.8) Other income 49.8 Other expenses (10.8) (Loss) before income taxes (38.0) Income tax (expense) (18.4) Net (loss) $ (56.4) Net reserves for loss and loss adjustment expenses $ 2,095.7 $ 1,874.4 $ 3,970.1 Ratios Loss ratio 74.4 % 71.1 % 72.8 % Acquisition cost ratio 19.1 17.7 18.4 General and administrative expense ratio 8.6 15.9 12.2 Expense ratio 27.7 33.6 30.6 Combined ratio 102.1 % 104.7 % 103.4 % ________________ (1) Non-operating expenses includes $18.2 million of expenses related to severance, retention and other costs, $12.9 million of impairment charges related to lease assets as a result of sub-leasing certain office space and $1.6 million of amortization of intangible assets and other non-operating expenses. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for six months ended June 30, 2023 and 2022: Six Months Ended June 30, 2023 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 875.7 $ 1,249.5 $ 2,125.2 Net written premiums 605.0 745.5 1,350.5 Net earned premiums 572.0 715.4 1,287.4 Underwriting Expenses Losses and loss adjustment expenses 297.2 419.9 717.1 Acquisition costs 105.7 87.2 192.9 General and administrative expenses 58.4 110.6 169.0 Underwriting income 110.7 97.7 208.4 Corporate and other expenses (1) (53.1) Non-operating expenses (10.6) Net investment income 129.4 Realized and unrealized investment gains 36.1 Realized and unrealized investment losses (18.1) Change in fair value of derivatives 19.6 Interest expense (42.9) Net realized and unrealized foreign exchange losses (13.7) Income before income taxes 255.1 Income tax (expense) (36.2) Net income $ 218.9 Net reserves for loss and loss adjustment expenses $ 1,441.2 $ 1,641.7 $ 3,082.9 Ratios Loss ratio 52.0 % 58.7 % 55.7 % Acquisition cost ratio 18.5 12.2 15.0 General and administrative expense ratio 10.2 15.5 13.1 Expense ratio 28.7 27.7 28.1 Combined ratio 80.7 % 86.4 % 83.8 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately. Six Months Ended June 30, 2022 Reinsurance Insurance Total ( $ in millions) Underwriting Revenues Gross written premiums $ 1,045.6 $ 1,305.7 $ 2,351.3 Net written premiums 783.7 722.4 1,506.1 Net earned premiums 600.8 726.4 1,327.2 Underwriting Expenses Losses and loss adjustment expenses 369.0 398.7 767.7 Acquisition costs 124.1 92.4 216.5 General and administrative expenses 69.7 116.8 186.5 Underwriting income 38.0 118.5 156.5 Corporate and other expenses (1) (37.5) Non-operating expenses (3.6) Net investment income 88.7 Realized and unrealized investment gains 2.5 Realized and unrealized investment losses (128.9) Realized loss on debt extinguishment — Change in fair value of loan notes issued by variable interest entities — Change in fair value of derivatives (84.9) Interest expense (9.1) Net realized and unrealized foreign exchange gains 75.2 Other income 2.9 Other expenses (8.7) Income before income taxes 53.1 Income tax (expense) (4.7) Net income $ 48.4 Net reserves for loss and loss adjustment expenses $ 1,190.4 $ 1,314.9 $ 2,505.3 Ratios Loss ratio 61.4 % 54.9 % 57.8 % Acquisition cost ratio 20.7 12.7 16.3 General and administrative expense ratio 11.6 16.1 14.1 Expense ratio 32.3 28.8 30.4 Combined ratio 93.7 % 83.7 % 88.2 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately.
Schedule of gross written premiums based on geographical areas	Geographical Areas . The following summary presents the Company’s gross written premiums based on the location of the insured risk for the twelve months ended December 31, 2022, 2021 and 2020. For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Australia/Asia $ 257.5 $ 275.8 $ 259.7 Europe 194.5 140.6 92.5 United Kingdom 485.8 393.2 369.0 United States & Canada (1) 2,715.7 2,301.8 2,267.5 Worldwide excluding United States (2) 24.2 31.5 23.1 Worldwide including United States (3) 541.7 592.2 501.2 Other (4) 119.3 203.3 185.5 Total $ 4,338.7 $ 3,938.4 $ 3,698.5 ________________ (1) “United States and Canada” comprises individual policies that insure risks specifically in the United States and/or Canada, but not elsewhere. (2) “Worldwide excluding the United States” consists of individual policies that insure global risks with the specific exclusion of the United States. (3) “Worldwide including the United States” consists of individual policies that insure global risks with the specific inclusion of the United States. (4)

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Investment Income	The following table summarizes investment income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Fixed income securities — Available for sale $ 95.6 $ 87.2 $ 106.5 Fixed income securities — Trading 57.0 30.2 32.8 Short-term investments — Available for sale 0.6 0.1 0.8 Short-term investments — Trading 0.1 — 0.5 Fixed term deposits (included in cash and cash equivalents) 6.6 0.7 6.4 Catastrophe bonds — Trading 0.3 0.9 1.4 Privately-held investments — Trading 24.3 18.2 20.9 Other investments, at fair value (1) 13.9 21.9 (2.0) Total 198.4 159.2 167.3 Investment expenses (10.3) (11.7) (12.7) Net investment income $ 188.1 $ 147.5 $ 154.6 ________________ (1) Other investments represents the Company’s investments in real estate funds and other special purpose vehicles. The movement in the year represents the change in fair value of the investment and has been included as part of our investment income. For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Fixed income securities — Available for sale $ 55.7 $ 44.5 Fixed income securities — Trading 47.8 18.9 Short-term investments — Available for sale 1.6 — Short-term investments — Trading 0.1 — Fixed term deposits (included in cash and cash equivalents) 17.3 0.5 Catastrophe bonds — Trading 1.1 0.1 Privately-held investments — Trading 21.5 8.8 Other investments, at fair value (1) (10.4) 20.7 Total 134.7 93.5 Investment expenses (5.3) (4.8) Net investment income $ 129.4 $ 88.7 __________________ (1)
Net Realized and Unrealized Investment Gains and Losses and Change in Unrealized Gains and Losses on Investments	The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 2.9 $ 22.7 $ 68.8 Fixed income securities — gross realized (losses) (58.4) (3.6) (1.8) Short-term investments — gross realized gains 1.0 2.0 0.5 Short-term investments — gross realized (losses) (0.5) (0.8) (0.4) Net change in expected credit (losses)/gains (5.0) (2.5) 0.4 Trading: Fixed income securities — gross realized gains 0.2 12.2 18.2 Fixed income securities — gross realized (losses) (1.8) (2.0) (3.8) Short-term investments — gross realized gains — 0.1 0.2 Short-term investments — gross realized (losses) — (0.3) (0.3) Privately-held investments — gross realized gains 0.7 0.6 — Privately-held investments — gross realized (losses) (0.1) (13.8) — Privately-held investments — net unrealized (losses)/gains (2.5) 18.1 (20.4) Catastrophe bonds — net unrealized gains/(losses) 0.2 (0.8) — Fixed income securities — net unrealized (losses) (113.9) (23.4) — Investments — equity method: Gross realized and unrealized gains/(losses) in MVI — 0.1 (0.4) Gross unrealized (losses)/gains in Multi-Line Reinsurer (0.4) 0.2 — Gross realized and unrealized (losses)/gains in Digital Risk — — (0.3) Gross realized gain on sale of Bene — — 1.8 Gross realized gain on sale of Crop Re — — 8.6 Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations $ (177.6) $ 8.8 $ 71.1 Change in available for sale net unrealized (losses)/gains: Fixed income securities (391.7) (157.6) 108.5 Income tax benefit/(expense) 23.9 (0.3) (0.5) Total change in net unrealized (losses)/gains, net of taxes recorded in other comprehensive income $ (367.8) $ (157.9) $ 108.0 The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the six months ended June 30, 2023 and 2022: For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 0.4 $ 1.4 Fixed income securities — gross realized (losses) (6.9) (29.9) Short-term investments — gross realized (losses) (0.2) — Cash and cash equivalents — gross realized gains 0.1 0.9 Cash and cash equivalents — gross realized (losses) (0.1) (0.2) Net change in expected credit gains/(losses) 3.7 (7.7) Trading: Fixed income securities — gross realized gains 0.3 — Fixed income securities — gross realized (losses) (1.1) (0.2) Short-term investments — gross realized gains 0.1 — Short-term investments — gross realized (losses) (0.2) — Privately-held investments — gross realized gains 0.1 0.2 Privately-held investments — net unrealized (losses) (9.0) (1.3) Catastrophe bonds — net unrealized (losses) (0.6) (0.1) Fixed income securities — net unrealized gains/(losses) 31.0 (89.6) Investments — equity method: Net change in realized and unrealized gains in Multi-Line Reinsurer 0.4 0.1 Total net realized and unrealized investment gains/(losses) recorded in the consolidated statement of operations $ 18.0 $ (126.4) Change in available for sale net unrealized gains/(losses): Fixed income securities gains/(losses) 12.3 (316.0) Income tax (expense)/benefit (1.6) 29.5 Total change in net unrealized gains/(losses), net of taxes recorded in other comprehensive income $ 10.7 $ (286.5)
Cost or Amortized Cost, Unrealized and Realized Gains and Losses and Estimated Fair Value of Available for Sale Investments	The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 __________________ (1) For the twelve months ended December 31, 2022, there was an increase in the CECL allowance on available-for-sale investments of $5.0 million (December 31, 2021 — $2.5 million decrease). As at December 31, 2021 Cost or Gross Gross Allowance Fair Market ($ in millions) U.S. government $ 1,066.2 $ 24.0 $ (5.9) $ — $ 1,084.3 U.S. agency 20.7 0.8 — — 21.5 Municipal 81.2 2.0 (0.5) (0.1) 82.6 Corporate 2,176.1 47.5 (13.0) (2.3) 2,208.3 Non-U.S. government-backed corporate 138.5 0.2 (1.9) — 136.8 Non-U.S. government 250.8 1.4 (1.2) (0.3) 250.7 Asset-backed 0.5 — — — 0.5 Non-agency commercial mortgage-backed 6.6 0.3 — — 6.9 Agency mortgage-backed 1,082.9 19.1 (12.0) — 1,090.0 Total fixed income securities — Available for sale 4,823.5 95.3 (34.5) (2.7) 4,881.6 Total short-term investments — Available for sale 10.1 — — — 10.1 Total $ 4,833.6 $ 95.3 $ (34.5) $ (2.7) $ 4,891.7 As at June 30, 2023 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,064.9 $ — $ (51.1) $ — $ 1,013.8 U.S. agency 8.6 — (0.4) — 8.2 Municipal 159.0 — (8.8) (0.7) 149.5 Corporate 2,031.9 2.4 (155.2) (3.2) 1,875.9 Non-U.S. government-backed corporate 119.6 — (8.7) — 110.9 Non-U.S. government 281.3 — (12.0) (0.1) 269.2 Non-agency commercial mortgage-backed 6.6 — (0.9) — 5.7 Agency mortgage-backed 559.3 — (84.3) — 475.0 Total fixed income securities — Available for sale 4,231.2 2.4 (321.4) (4.0) 3,908.2 Total short-term investments — Available for sale 169.3 — — — 169.3 Total $ 4,400.5 $ 2.4 $ (321.4) $ (4.0) $ 4,077.5 __________________ (1) For the six months ended June 30, 2023, there was a decrease in the CECL allowance on available-for-sale investments of $3.7 million (December 31, 2022 — $5.0 million increase). As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6
Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Trading Investments in Fixed Income Maturities	The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 $ 0.6 $ (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Equity securities 6.6 — — 6.6 Short-term investments 25.6 — — 25.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 As at December 31, 2021 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 115.9 $ 0.6 $ (0.2) $ 116.3 Municipal 3.9 0.1 — 4.0 Corporate 95.7 1.9 (0.8) 96.8 High yield loans 77.2 0.1 (0.4) 76.9 Non-U.S. government-backed corporate 13.3 — (0.2) 13.1 Non-U.S. government 34.9 — (0.4) 34.5 Asset-backed 784.3 3.3 (1.9) 785.7 Agency mortgage-backed 30.3 0.2 (0.3) 30.2 Total fixed income securities — Trading 1,155.5 6.2 (4.2) 1,157.5 Short-term investments — Trading 2.0 — — 2.0 Catastrophe bonds — Trading 5.3 — (1.9) 3.4 Privately-held investments — Trading Commercial mortgage loans $ 212.0 0.4 (0.9) $ 211.5 Middle market loans 66.9 — (1.5) 65.4 Asset-backed securities 26.8 — (0.2) 26.6 Equity securities 3.5 0.1 — 3.6 Total privately-held investments — Trading 309.2 0.5 (2.6) 307.1 Total Investments — Trading $ 1,472.0 $ 6.7 $ (8.7) $ 1,470.0 As at June 30, 2023 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 241.9 $ — $ (6.9) $ 235.0 Municipal 3.4 — (0.3) 3.1 Corporate 176.9 0.3 (11.8) 165.4 High yield loans 86.1 1.2 (0.7) 86.6 Non-U.S. government-backed corporate 10.1 — (0.5) 9.6 Non-U.S. government 35.8 — (1.7) 34.1 Asset-backed 975.2 1.0 (51.6) 924.6 Agency mortgage-backed 23.3 — (3.2) 20.1 Total fixed income securities — Trading 1,552.7 2.5 (76.7) 1,478.5 Short-term investments — Trading 11.0 — — 11.0 Catastrophe bonds — Trading 2.4 — — 2.4 Privately-held investments — Trading Commercial mortgage loans $ 305.5 $ 1.3 $ (11.8) $ 295.0 Middle market loans 104.1 — (2.0) 102.1 Asset-backed securities 59.5 — (1.1) 58.4 Global corporate securities 14.9 — (0.1) 14.8 Equity securities 12.1 — — 12.1 Total privately-held investments — Trading 496.1 1.3 (15.0) 482.4 Total Investments — Trading $ 2,062.2 $ 3.8 $ (91.7) $ 1,974.3 As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 0.6 (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Short-term investments 25.6 — — 25.6 Equity securities 6.6 — — 6.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7
Schedule of Commercial Mortgage and Middle Market Loans	The following table presents the type of commercial mortgage loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 115.3 36.9 101.6 48.1 Hotels 108.0 34.6 68.8 32.5 Office building 42.1 13.5 33.9 16.0 Other commercial 41.4 13.3 7.2 3.4 Retail 3.3 1.1 — — Industrial 2.0 0.6 — — Total commercial mortgage loans $ 312.1 100 % 211.5 100 % Geographic Region U.S. 269.8 86.4 183.7 86.9 International 42.3 13.6 27.8 13.1 Total commercial mortgage loans $ 312.1 100 % 211.5 100 % As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 19.8 18.5 20.9 32.0 Financials 53.1 49.7 6.1 9.3 Industrials 18.7 17.5 18.7 28.5 Consumer discretionary 4.9 4.6 4.3 6.6 Energy 5.7 5.3 5.6 8.6 Consumer staples — — 4.9 7.5 Information technology 4.7 4.4 4.9 7.5 Total middle market mortgage loans $ 106.9 100 % $ 65.4 100 % Geographic Region U.S. 64.1 59.9 56.2 85.9 International 42.8 40.1 9.2 14.1 Total middle market loans $ 106.9 100 % $ 65.4 100 % As at June 30, 2023 As at December 31, 2022 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 107.8 36.6 115.3 36.9 Hotels 98.1 33.3 108.0 34.6 Office building 45.9 15.5 42.1 13.5 Other commercial 37.9 12.8 41.4 13.3 Retail 3.3 1.1 3.3 1.1 Industrial 2.0 0.7 2.0 0.6 Total commercial mortgage loans $ 295.0 100 % 312.1 100 % Geographic Region U.S. 263.6 89.4 269.8 86.4 International 31.4 10.6 42.3 13.6 Total commercial mortgage loans $ 295.0 100 % 312.1 100 % As at June 30, 2023 As at December 31, 2022 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 20.0 19.6 19.8 18.5 Financials 48.3 47.3 53.1 49.7 Industrials 18.6 18.2 18.7 17.5 Consumer discretionary 4.9 4.8 4.9 4.6 Energy 5.6 5.5 5.7 5.3 Information technology 4.7 4.6 4.7 4.4 Total middle market mortgage loans $ 102.1 100 % $ 106.9 100 % Geographic Region U.S. 59.4 58.2 64.1 59.9 International 42.7 41.8 42.8 40.1 Total middle market loans $ 102.1 100 % $ 106.9 100 %
Credit Quality Indicators of Commercial Mortgage and Middle Market Loans	A loan-to-value ratio in excess of 100% indicates the unpaid loan amount exceeds the underlying collateral. The following table represents the loan-to-value ratio of the commercial mortgage loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 41.1 $ — 50% to 60% 248.3 131.2 61% to 70% 22.7 80.3 Commercial mortgage loans $ 312.1 $ 211.5 As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 63.5 $ 11.0 50% to 60% 16.4 9.2 61% to 70% 27.0 15.8 71% to 80% — 5.6 81% to 100% — 12.0 Greater than 100% — 11.8 Middle market loans $ 106.9 $ 65.4 As at June 30, 2023 As at December 31, 2022 (in millions) Less than 50% $ 47.5 $ 41.1 50% to 60% 227.3 248.3 61% to 70% 20.2 22.7 Commercial mortgage loans $ 295.0 $ 312.1 As at June 30, 2023 As at December 31, 2022 (in millions) Less than 50% $ 63.5 $ 63.5 50% to 60% 23.3 16.4 61% to 70% 15.3 27.0 Middle market loans $ 102.1 $ 106.9
Debt Service and Fixed Charge Coverage Ratios	The following table represents the debt-service coverage ratio of the commercial mortgage loan portfolio, excluding those that are non-performing and construction loans which are still under development, as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 106.1 $ 66.3 1.00 - 1.20x 186.1 62.4 Less than 1.00x — 18.8 Commercial mortgage loans (1) $ 292.2 $ 147.5 __________________ (1) As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 95.2 $ 25.8 1.00 - 1.20x 3.8 22.8 Less than 1.00x 7.9 16.8 Middle market loans $ 106.9 $ 65.4 As at June 30, 2023 As at December 31, 2022 (in millions) Greater than 1.20x $ 112.3 $ 106.1 1.00 - 1.20x 182.7 186.1 Less than 1.00x — — Commercial mortgage loans (1) $ 295.0 $ 292.2 ________________ (1) As at June 30, 2023, we have non-performing loans of $Nil (December 31, 2022 — $Nil) and construction loans of $Nil (December 31, 2022 — $19.9 million) which only generate income when the construction is completed. As no income is currently being generated on these loans, they are not included in the table above. The total value of commercial mortgage loans is $295.0 million as at June 30, 2023 (December 31, 2022 — $312.1 million). As at June 30, 2023 As at December 31, 2022 (in millions) Greater than 1.20x $ 78.9 $ 95.2 1.00 - 1.20x 3.8 3.8 Less than 1.00x 19.4 7.9 Middle market loans $ 102.1 $ 106.9
Other Investments	The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the twelve months ended December 31, 2022 and 2021: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Distribution received — — — — Unrealized (loss)/gain for the twelve months to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investment as at December 31, 2022 0.8 5.2 0.2 6.2 Opening undistributed value of investment as at January 1, 2021 $ — $ 0.5 $ 0.4 $ 0.9 Investment in the period 0.4 2.5 0.3 3.2 Distribution received — — (0.5) (0.5) Unrealized gain for the twelve months to December 31, 2021 0.1 0.2 — 0.3 Closing value of investments at December 31, 2021 $ 0.5 $ 3.2 $ 0.2 $ 3.9 The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the six months ended June 30, 2023 and the twelve months ended December 31, 2022: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2023 $ 0.8 $ 5.2 $ 0.2 $ 6.2 Investment in the period — 0.4 — 0.4 Unrealized gain for the period to June 30, 2023 — 0.4 — 0.4 Closing value of investment as at June 30, 2023 0.8 6.0 0.2 7.0 Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Unrealized (loss)/gain for the period to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investments at December 31, 2022 $ 0.8 $ 5.2 $ 0.2 $ 6.2
Summary of Fixed Maturities	Actual maturities may differ from contractual maturities because issuers of securities may have the right to call or prepay obligations with or without call or prepayment penalties. As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6 At December 31, 2021 Amortized Fair Market Average ($ in millions) Due one year or less $ 545.1 $ 549.0 AA- Due after one year through five years 2,057.2 2,087.5 AA- Due after five years through ten years 1,090.5 1,106.3 A+ Due after ten years 40.7 41.4 A- Total — Government and corporate 3,733.5 3,784.2 Non-agency commercial mortgage-backed 6.6 6.9 AA+ Agency mortgage-backed 1,082.9 1,090.0 AA+ Asset-backed 0.5 0.5 AAA Total fixed income securities — Available for sale $ 4,823.5 $ 4,881.6 As at June 30, 2023 Amortized Fair Market Average ($ in millions) Due one year or less $ 242.4 $ 236.5 AA Due after one year through five years 2,736.2 2,594.7 AA- Due after five years through ten years 684.9 595.2 A+ Due after ten years 1.8 1.1 BB Total — Government and corporate 3,665.3 3,427.5 Non-agency commercial mortgage-backed 6.6 5.7 AA+ Agency mortgage-backed 559.3 475.0 AA+ Total fixed income securities — Available for sale $ 4,231.2 $ 3,908.2 As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6
Aggregate Fair Value and Gross Unrealized Loss by Type of Security	The following tables summarize, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Company’s available for sale portfolio as at December 31, 2022 and December 31, 2021: December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166 December 31, 2021 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 309.1 $ (4.0) $ 29.3 $ (1.9) $ 338.4 $ (5.9) 51 U.S. agency 6.1 — — — 6.1 — 5 Municipal 29.7 (0.5) — — 29.7 (0.5) 20 Corporate 804.6 (11.7) 23.6 (1.3) 828.2 (13.0) 400 Non-U.S. government-backed corporate 114.4 (1.9) — — 114.4 (1.9) 10 Non-U.S. government 181.8 (1.2) 3.1 — 184.9 (1.2) 35 Agency mortgage-backed 564.5 (11.6) 16.0 (0.4) 580.5 (12.0) 116 Total fixed income securities — Available for sale 2,010.2 (30.9) 72.0 (3.6) 2,082.2 (34.5) 637 Total short-term investments — Available for sale 4.4 — — — 4.4 — 7 Total $ 2,014.6 $ (30.9) $ 72.0 $ (3.6) $ 2,086.6 $ (34.5) 644 June 30, 2023 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 494.8 $ (12.8) $ 519.1 $ (38.3) $ 1,013.9 $ (51.1) 105 U.S. agency 7.0 (0.4) 1.1 — 8.1 (0.4) 4 Municipal 90.9 (3.7) 58.7 (5.1) 149.6 (8.8) 60 Corporate 467.4 (13.1) 1,254.7 (142.1) 1,722.1 (155.2) 727 Non-U.S. government-backed corporate 5.2 — 105.7 (8.7) 110.9 (8.7) 16 Non-U.S. government 80.1 (1.2) 182.2 (10.8) 262.3 (12.0) 61 Non-agency commercial mortgage-backed — — 5.6 (0.9) 5.6 (0.9) 1 Agency mortgage-backed 18.4 (1.3) 455.6 (83.0) 474.0 (84.3) 214 Total fixed income securities — Available for sale 1,163.8 (32.5) 2,582.7 (288.9) 3,746.5 (321.4) 1,188 Total short-term investments — Available for sale 11.8 — — — 11.8 — 5 Total $ 1,175.6 $ (32.5) $ 2,582.7 $ (288.9) $ 3,758.3 $ (321.4) 1,193 December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed securities 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Financial Assets Measured on Recurring Basis	The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Asset-backed — — — — Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Held for trading financial assets, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Privately-held investments trading, at fair value — — 533.0 533.0 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 56.2 — 56.2 Liabilities under derivative contracts — foreign exchange contracts — (3.2) — (3.2) Liabilities under derivative contracts — loss portfolio transfer (2) — — (31.7) (31.7) Total 1,428.7 3,949.6 501.3 6,100.9 ________________ (1) Other investments represents our investments in real estate and other special purpose vehicles and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. At December 31, 2021 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 1,084.3 $ — $ — $ 1,084.3 U.S. agency — 21.5 — 21.5 Municipal — 82.6 — 82.6 Corporate — 2,208.3 — 2,208.3 Non-U.S. government-backed corporate — 136.8 — 136.8 Non-U.S. government 164.4 86.3 — 250.7 Asset-backed — 0.5 — 0.5 Non-agency commercial mortgage-backed — 6.9 — 6.9 Agency mortgage-backed — 1,090.0 — 1,090.0 Total fixed income securities available for sale, at fair value 1,248.7 3,632.9 — 4,881.6 Short-term investments available for sale, at fair value 6.5 3.6 — 10.1 Held for trading financial assets, at fair value U.S. government 116.3 — — 116.3 Municipal — 4.0 — 4.0 Corporate — 96.8 — 96.8 Non-U.S. government-backed corporate — 13.1 — 13.1 High yield loans — 76.9 — 76.9 Non-U.S. government 11.9 22.6 — 34.5 Asset-backed — 785.7 — 785.7 Agency mortgage-backed — 30.2 — 30.2 Total fixed income securities trading, at fair value 128.2 1,029.3 — 1,157.5 Short-term investments trading, at fair value 1.1 0.9 — 2.0 Privately-held investments — — 307.1 307.1 Catastrophe bonds trading, at fair value — 3.4 — 3.4 Other investments (1) — — — 151.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 12.9 — 12.9 Liabilities under derivative contracts — foreign exchange contracts — (13.3) — (13.3) Total $ 1,384.5 $ 4,669.7 $ 307.1 $ 6,512.6 ________________ (1) Other investments represents our investments in real estate funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 1,013.8 $ — $ — $ 1,013.8 U.S. agency — 8.2 — 8.2 Municipal — 149.5 — 149.5 Corporate — 1,875.9 — 1,875.9 Non-U.S. government-backed corporate — 110.9 — 110.9 Non-U.S. government 192.7 76.5 — 269.2 Non-agency commercial mortgage-backed — 5.7 — 5.7 Agency mortgage-backed — 475.0 — 475.0 Total fixed income securities available for sale, at fair value 1,206.5 2,701.7 — 3,908.2 Short-term investments available for sale, at fair value 169.2 0.1 — 169.3 Fixed income securities, trading, at fair value 235.0 — — 235.0 Municipal — 3.1 — 3.1 Corporate — 165.4 — 165.4 Non-U.S. government-backed corporate — 9.6 — 9.6 High yield loans — 86.6 — 86.6 Non-U.S. government 12.7 21.4 — 34.1 Asset-backed — 924.6 — 924.6 Agency mortgage-backed — 20.1 — 20.1 Total fixed income securities trading, at fair value 247.7 1,230.8 — 1,478.5 Short-term investments trading, at fair value 9.1 1.9 — 11.0 Privately-held investments trading, at fair value — — 482.4 482.4 Catastrophe bonds trading, at fair value — 2.4 — 2.4 Other investments (1) — — — 213.4 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 17.2 — 17.2 Derivative liabilities — foreign exchange contracts — (13.4) — (13.4) Derivative liabilities — loss portfolio transfer (2) — — (23.4) (23.4) Total 1,632.5 3,940.7 459.0 6,245.6 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Fixed income securities, trading, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Privately-held investments — — 533.0 533.0 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 56.2 — 56.2 Derivative liabilities — foreign exchange contracts — (3.2) — (3.2) Derivative liabilities — loss portfolio transfer — — (31.7) (31.7) Total $ 1,428.7 $ 3,949.6 $ 501.3 $ 6,100.9 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.”
Fair Value, Measured on a Recurring Basis, Gain (Loss) Included in Earnings	The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Lev el 3 inputs for the twelve months ended December 31, 2022 and December 31, 2021: Twelve Months Ended December 31, 2022 Balance at beginning of year Purchases and issuances Transfers in/(out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of year Change in unrealized investment gains (losses) relating to assets held at end of year Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Liabilities under derivative contracts - loss $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Twelve Months Ended December 31, 2021 Assets Privately-held investments — trading Commercial mortgage loans $ 163.6 $ 169.9 $ — $ (122.5) $ 0.5 $ 211.5 $ (0.5) Middle market loans 112.1 5.6 — (56.1) 3.7 65.3 (1.5) Asset-backed securities 18.6 10.0 — (1.8) (0.1) 26.7 (0.2) Equity securities 5.0 0.1 — (1.6) 0.1 3.6 — Preference shares — 19.5 (19.5) — — — — Total Level 3 assets $ 299.3 $ 205.1 $ (19.5) $ (182.0) $ 4.2 $ 307.1 $ (2.2) Valuation of Fixed Income Securities . The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Level 3 inputs for the six months ended June 30, 2023 and the twelve months ended December 31, 2022: Six Months Ended June 30, 2023 Balance at beginning of period Purchases and issuances Transfers (out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of period Change in unrealized investment gains (losses) relating to assets held at end of period Assets Privately-held investments — trading Commercial mortgage loans $ 312.1 $ 15.9 $ — $ (23.2) $ (9.8) $ 295.0 $ (10.5) Middle market loans 106.9 0.1 — (5.4) 0.5 102.1 (2.0) Asset-backed securities 66.8 — (5.5) (3.8) 0.9 58.4 (1.1) Global corporate securities 15.0 — — (0.2) — 14.8 (0.1) Equity securities 6.6 7.0 (1.2) (0.2) (0.1) 12.1 — Short-term investments 25.6 — — (25.6) — — — Total Level 3 assets $ 533.0 $ 23.0 $ (6.7) $ (58.4) $ (8.5) $ 482.4 $ (13.7) Liabilities Derivative liabilities - loss portfolio transfer $ (31.7) $ — $ — $ — $ 8.3 $ (23.4) $ — Total Level 3 liabilities $ (31.7) $ — $ — $ — $ 8.3 $ (23.4) $ — Twelve Months Ended December 31, 2022 Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Derivative liabilities - loss portfolio transfer $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ —
Fair Value Inputs, and Valuation Techniques	The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at December 31, 2022: At December 31, 2022 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 200.7 Discounted cash flow Discount rate 3.9 % 9.4 % 5.3 % Commercial mortgage loans 85.8 Transaction Value n/a n/a n/a n/a Commercial mortgage loans 25.6 Liquidation method n/a n/a n/a n/a Middle market loans 106.9 Discounted cash flow Discount rate 7.4 % – 18.5 % 9.9 % Asset-backed securities 66.8 Discounted cash flow Discount rate 5.8 % – 9.3 % 6.7 % Global corporate securities 15.0 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Equity securities 5.3 Discounted cash flow Discount rate 9.0 % – 12.5 % 9.1 % Equity securities 1.3 Transaction Value n/a n/a n/a n/a Short-term investments 25.6 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Total $ 533.0 The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at June 30, 2023: At June 30, 2023 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 270.0 Discounted cash flow Discount rate 3.7% - 11.2% 6.2% Commercial mortgage loans 25.0 3rd party NAV n/a n/a n/a n/a Middle market loans 102.1 Discounted cash flow Discount rate 7.6% - 20.9% 10.8% Asset-backed securities 58.4 Discounted cash flow Discount rate 5.8% - 9.3% 6.8% Global corporate securities 14.8 Discounted cash flow Discount rate 6.4% - 7.4% 6.4% Equity securities 12.1 Discounted cash flow Discount rate 8.6% - 8.6% 8.6% Total $ 482.4

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2023
Reinsurance Disclosures [Abstract]
Summary of Assumed and Ceded Reinsurance on Premiums Written, Premiums Earned and Insurance Losses and Loss Adjustment Expenses	The effect of assumed and ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the twelve months ended December 31, 2022, 2021 and 2020 was as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Premiums written: Direct $ 2,531.7 $ 2,341.4 $ 2,042.1 Assumed 1,807.0 1,597.0 1,656.4 Ceded (1,442.7) (1,350.7) (1,120.7) Net premiums written $ 2,896.0 $ 2,587.7 $ 2,577.8 Premiums earned: Direct $ 2,370.8 $ 2,139.1 $ 2,026.4 Assumed 1,617.2 1,479.2 1,612.0 Ceded (1,299.3) (1,207.8) (1,110.9) Net premiums earned $ 2,688.7 $ 2,410.5 $ 2,527.5 Insurance losses and loss adjustment expenses: Direct $ 1,574.2 $ 1,499.8 $ 1,479.6 Assumed 939.5 1,000.6 1,134.5 Ceded (833.7) (807.1) (773.3) Net insurance losses and loss adjustment expenses $ 1,680.0 $ 1,693.3 $ 1,840.8 The effect of ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the six months ended June 30, 2023 and 2022 was as follows: Six Months Ended June 30, 2023 2022 ($ in millions) Premiums written: Insurance $ 1,249.5 $ 1,305.7 Reinsurance 875.7 1,045.6 Ceded (774.7) (845.2) Net premiums written $ 1,350.5 $ 1,506.1 Premiums earned: Insurance $ 1,203.6 $ 1,171.5 Reinsurance 755.7 776.9 Ceded (671.9) (621.2) Net premiums earned $ 1,287.4 $ 1,327.2 Insurance losses and loss adjustment expenses: Insurance $ 691.7 $ 719.2 Reinsurance 353.4 402.4 Ceded (328.0) (353.9) Net insurance losses and loss adjustment expenses $ 717.1 $ 767.7

Derivative Contracts (Tables)

Derivative Contracts (Tables)	6 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at December 31, 2022 and 2021: As at December 31, 2022 As at December 31, 2021 Derivatives Not Designated as Hedging Instruments Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivatives at Fair Value $ 945.8 $ 41.9 $ 759.8 $ 12.9 Foreign Exchange Contracts Liabilities under Derivative Contracts $ 729.5 $ (3.2) $ 785.9 $ (12.4) Loss Portfolio Transfer Liability - Embedded Derivative (2) Liabilities under Derivative Contracts — $ (31.7) — — ________________ (1) Fair value is net of $3.7 million of cash collateral (December 31, 2021 — $2.1 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. Refer to Note 7 for further information. As at December 31, 2022 As at December 31, 2021 Derivatives Designated as Hedging Instruments Under ASC 815 Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivatives at Fair Value $ 109.7 $ 14.3 $ — $ — Foreign Exchange Contracts Liabilities under Derivative Contracts $ — $ — $ 143.1 $ (0.9) The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Derivatives Not Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivative assets $ 670.6 $ 7.2 $ 945.8 $ 41.9 Foreign Exchange Contracts Derivative liabilities $ 1,213.4 $ (13.4) $ 729.5 $ (3.2) Loss Portfolio Transfer Liability - Embedded Derivative (2) Derivative liabilities — $ (23.4) — (31.7) ________________ (1) Fair value is net of $2.7 million of cash collateral (December 31, 2022 — $3.7 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. As at June 30, 2023 As at December 31, 2022 Derivatives Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivative assets $ 54.7 $ 10.0 $ 109.7 $ 14.3
Gain/(Loss) Recognized in Income on Derivative	The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging” for the twelve months ended December 31, 2022 and 2021: Amount of (Loss)/Gain Recognized on Derivatives For the Twelve Months Ended Location of Gain/(Loss) December 31, 2022 December 31, 2021 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives (80.5) (35.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations 5.9 (5.7) Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income 15.4 (6.2) The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging ” for the six months ended June 30, 2023 and 2022: For the Six Months Ended Location of Gain/(Loss) June 30, 2023 June 30, 2022 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives 19.6 (84.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations (3.7) 2.8 Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income (4.3) (6.4)

Deferred Policy Acquisition C_2

Deferred Policy Acquisition Costs (Tables)	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Reconciliation of beginning and ending deferred policy acquisition costs	The following table represents a reconciliation of beginning and ending deferred acquisition costs for the twelve months ended December 31, 2022 and 2021: Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 ($ in millions) Balance at the beginning of the period $ 290.8 $ 306.6 Acquisition costs deferred 460.0 398.3 Amortization of deferred acquisition costs (431.8) (414.1) Balance at the end of the period $ 319.0 $ 290.8

Reserves for Losses and Adjus_3

Reserves for Losses and Adjustment Expenses (Tables)	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the twelve months ended December 31, 2022, 2021 and 2020: As at December 31, 2022 2021 2020 ($ in millions) Provision for losses and LAE at the start of the year $ 7,611.8 $ 7,165.3 $ 6,951.8 Less reinsurance recoverable (3,298.1) (3,195.2) (2,319.8) Net loss and LAE at the start of the year 4,313.7 3,970.1 4,632.0 Net loss and LAE expenses disposed (1) (1,840.1) — (818.5) Movement in net provision for losses and LAE for claims incurred: Current year 1,651.9 1,648.2 1,841.7 Prior years 28.1 45.1 (0.9) Total incurred 1,680.0 1,693.3 1,840.8 Net Losses and LAE payments for claims incurred: Current year (192.7) (729.1) (404.9) Prior years (1,098.4) (580.7) (1,359.7) Total paid (1,291.1) (1,309.8) (1,764.6) Foreign exchange (gains)/losses (49.3) (39.9) 80.4 Net losses and LAE reserves at the end of the year 2,813.2 4,313.7 3,970.1 Plus reinsurance recoverable on unpaid losses at the end of the year 4,897.7 3,298.1 3,195.2 Provision for losses and LAE at the end of the year $ 7,710.9 $ 7,611.8 $ 7,165.3 ________________ (1) The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the six months at June 30, 2023 and June 30, 2022: As at June 30, As at June 30, 2023 2022 ($ in millions) Provision for losses and LAE at the start of the period $ 7,710.9 $ 7,611.8 Less reinsurance recoverable (4,897.7) (3,298.1) Net loss and LAE at the start of the period 2,813.2 4,313.7 Net loss and LAE expenses transferred (1) — (1,840.1) Movement in net provision for losses and LAE for claims incurred: Current year 723.5 775.0 Prior years (6.4) (7.3) Total incurred 717.1 767.7 Net Losses and LAE payments for claims incurred: Current year (30.8) (35.5) Prior years (438.6) (616.9) Total paid (469.4) (652.4) Foreign exchange losses/(gains) 22.0 (83.6) Net losses and LAE reserves at the end of the period 3,082.9 2,505.3 Plus reinsurance recoverable on unpaid losses at the end of the period 4,658.0 5,006.5 Provision for losses and LAE at the end of the period $ 7,740.9 $ 7,511.8 __________________ (1)
Short-duration Insurance Contracts, Claims Development	The following tables show an analysis of incurred claims and allocated loss adjustment expenses, net of reinsurance and cumulative paid claims and allocated claim adjustment expenses, net of reinsurance as at December 31, 2022, 2021, 2020, 2019 2018, 2017, 2016, 2015, 2014 and 2013. Under the LPT agreement, the Company has reinsured net losses incurred on all accident years 2019 and prior. This has resulted in total incurred claims, IBNR and loss adjustment expenses in the loss development triangles for 2019 and prior to be Nil. The loss development triangles are derived from all business written by the Company as although a limited number of contracts are written which have durations of greater than one year the contracts do not meet the definition of a long duration contract. All amounts included in the following tables related to transactions denominated in a foreign currency have been translated into U.S. Dollars using the exchange rates in effect at December 31, 2022. The Company has chosen to disaggregate the business in its Insurance segment, for the purposes of these loss development triangles as: Property; Casualty; Marine Aviation and Energy; and Financial and Professional insurance lines. The Company considers that this presentation of its Insurance lines loss development triangles more precisely reflects meaningful trending information. The Company presents its loss development triangles for the Reinsurance segment in line with the reportable reinsurance lines: Property Catastrophe and Other Property; Casualty; and Specialty. Property Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Accident For the Years Ended December 31, Cumulative Number of Reported Claims Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 126.7 114.4 114.2 109.9 110.9 109.0 109.3 109.5 102.1 106.1 — — 2014 162.6 154.9 132.4 133.0 132.2 130.7 130.1 125.2 131.1 — 9,949 2015 233.3 199.0 193.9 196.3 196.9 193.9 179.6 189.2 — 11,549 2016 233.9 245.0 240.0 241.3 242.5 233.4 244.8 — 10,773 2017 290.4 253.7 246.8 248.1 280.9 247.7 — 9,717 2018 196.3 198.1 182.2 196.2 177.3 — 8,308 2019 122.5 126.5 104.1 107.8 — 6,852 2020 199.9 195.9 205.1 24.4 7,542 2021 204.6 199.5 38.2 6,583 2022 163.9 62.9 4,171 Total $ 1,772.5 Property Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 37.5 73.7 86.8 98.6 103.0 105.8 107.6 107.9 106.8 106.1 2014 39.9 85.2 112.5 122.0 126.0 127.3 128.7 129.9 131.1 2015 56.3 138.3 165.1 174.1 190.1 188.9 190.4 189.2 2016 65.7 166.1 198.1 219.2 228.6 233.7 244.8 2017 95.0 185.0 217.2 237.9 242.1 247.7 2018 60.3 153.6 176.1 173.0 177.3 2019 48.0 88.6 99.3 107.8 2020 60.1 122.9 150.1 2021 58.2 118.6 2022 40.8 Total $ 1,513.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 259.0 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 259.0 Casualty Insurance Lines As at December 31, 2022 Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance Cumulative Number of Reported Claims Accident For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 128.6 112.8 111.6 116.8 99.8 101.1 101.4 100.0 107.8 86.7 — 3,392 2014 139.9 122.6 134.2 124.0 131.0 134.9 131.8 137.9 107.4 — 3,914 2015 197.9 217.9 180.5 197.5 230.1 228.3 250.4 197.2 — 4,775 2016 211.5 182.5 177.6 184.2 195.1 247.4 163.3 — 4,818 2017 176.3 169.9 173.4 190.5 234.6 154.4 — 5,495 2018 119.4 122.5 132.2 169.7 94.4 — 5,500 2019 122.0 144.4 155.3 88.3 — 5,198 2020 131.1 139.3 138.7 72.1 3,755 2021 170.5 185.6 119.7 3,356 2022 201.1 132.1 2,709 Total $ 1,417.1 Casualty Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 2.1 25.1 38.2 51.2 65.9 77.9 82.0 83.9 84.0 86.7 2014 2.5 12.6 31.5 57.3 70.1 93.1 105.4 104.0 107.4 2015 3.0 16.4 55.1 90.2 135.0 163.6 174.5 197.2 2016 4.0 22.0 38.6 79.7 106.1 128.8 163.3 2017 3.4 22.3 51.2 93.4 110.3 154.4 2018 3.0 27.2 41.4 65.5 94.4 2019 6.2 16.7 68.0 88.3 2020 — 9.2 36.1 2021 3.00 8.8 2022 23.2 Total $ 959.8 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 457.3 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 457.3 Marine, Aviation and Energy Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Cumulative Number of Reported Claims For the Years Ended December 31, Total of IBNR Plus Expected Development on Reported Claims Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 319.4 332.1 340.7 324.3 331.5 345.0 343.6 338.7 346.5 319.7 — 4,179 2014 308.6 312.2 297.2 308.9 304.5 311.4 300.7 317.6 279.1 — 4,058 2015 295.3 297.0 279.3 283.7 307.2 309.9 327.3 302.7 — 4,076 2016 258.8 229.0 227.5 227.9 217.7 224.3 199.2 — 4,431 2017 209.3 199.9 206.2 213.7 231.5 205.3 — 6,059 2018 170.1 207.1 207.9 238.8 169.7 — 5,153 2019 145.5 152.8 151.1 124.0 — 3,662 2020 110.2 111.2 125.7 17.5 3,856 2021 93.0 96.1 18.3 4,863 2022 107.7 58.8 3,810 Total $ 1,929.2 Marine, Aviation and Energy Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 41.2 130.9 203.9 234.1 263.5 283.1 299.1 309.3 309.0 319.7 2014 53.2 116.0 188.1 208.6 231.3 249.5 261.7 274.2 279.1 2015 44.6 122.5 172.7 192.1 220.0 255.5 277.5 302.7 2016 30.8 81.9 141.3 163.1 189.5 197.3 199.2 2017 40.0 97.0 139.6 167.6 155.7 205.3 2018 26.7 104.3 132.6 154.7 169.7 2019 33.4 72.4 117.5 124.0 2020 28.5 66.4 88.6 2021 23.5 52.3 2022 24.9 Total $ 1,765.5 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 163.7 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 163.7 Financial and Professional Insurance Lines Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 104.3 98.7 103.1 99.6 98.6 89.9 88.8 95.1 101.0 82.9 — 606 2014 133.2 128.8 127.4 117.7 128.9 118.0 118.8 124.3 118.9 — 794 2015 171.9 173.4 183.1 187.1 188.0 183.0 189.9 163.9 — 1,085 2016 188.4 209.3 213.7 199.7 182.9 189.0 163.2 — 1,244 2017 203.9 179.6 184.5 185.2 208.8 166.7 — 1,737 2018 153.7 169.4 151.2 163.2 125.4 — 4,643 2019 246.8 259.6 253.9 195.2 — 23,831 2020 346.3 346.2 336.2 118.0 105,947 2021 284.5 302.8 170.4 34,942 2022 314.8 265.2 3,487 Total $ 1,970.0 Financial and Professional Insurance Lines Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 7.9 20.6 30.6 64.6 62.8 71.1 73.2 76.4 79.9 82.9 2014 2.8 30.2 52.7 71.1 78.5 84.0 90.9 102.3 118.9 2015 13.5 43.1 69.5 88.6 108.8 137.6 144.1 163.9 2016 14.8 70.7 100.7 128.7 124.6 133.8 163.2 2017 27.1 51.0 83.0 116.2 135.6 166.7 2018 17.4 71.6 97.8 113.3 125.4 2019 26.8 86.2 136.8 195.2 2020 47.2 120.8 174.2 2021 42.8 90.2 2022 17.5 Total $ 1,298.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance $ 671.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 671.9 Property Catastrophe and Other Property Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 212.3 193.7 184.1 173.1 171.7 168.5 165.8 162.9 159.5 156.3 — 832 2014 185.8 172.6 157.1 145.7 145.9 141.1 141.2 140.1 138.1 — 900 2015 210.0 183.7 173.8 153.5 168.9 168.9 177.2 160.6 — 1,048 2016 264.2 264.6 263.2 242.1 237.7 230.1 229.8 — 1,307 2017 550.7 529.4 511.7 500.4 595.5 447.7 — 1,953 2018 323.5 362.8 356.0 571.0 304.5 — 1,780 2019 237.3 249.6 358.7 203.6 — 1,399 2020 317.5 402.1 348.9 81.0 1,379 2021 647.3 472.7 196.9 1,411 2022 392.3 266.7 950 Total $ 2,854.5 Property Catastrophe and Other Property Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 33.9 95.7 142.6 154.1 158.6 160.1 161.6 156.0 156.0 156.3 2014 36.9 98.5 124.4 133.7 137.4 136.0 137.6 137.8 138.1 2015 35.6 93.6 124.2 136.7 153.6 155.9 159.5 160.6 2016 55.8 160.5 200.9 211.6 224.4 230.7 229.8 2017 123.0 355.4 413.5 437.1 433.7 447.7 2018 122.1 290.1 296.8 315.3 304.5 2019 28.1 143.9 191.4 203.6 2020 41.8 165.5 237.3 2021 75.0 233.2 2022 65.5 Total $ 2,176.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 677.9 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 677.9 Casualty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 211.7 226.7 221.6 219.1 202.3 197.7 200.3 197.9 191.6 151.9 — 1,700 2014 201.8 204.0 212.3 205.5 199.0 202.1 198.0 191.1 144.7 — 1,843 2015 191.1 197.6 207.3 209.8 207.5 203.7 198.8 135.1 — 2,038 2016 229.3 241.4 241.0 251.0 258.5 258.5 174.6 — 2,153 2017 241.0 239.1 249.7 248.9 265.5 147.7 — 2,166 2018 226.0 255.0 262.5 264.3 130.4 — 2,002 2019 232.5 253.1 252.0 82.1 — 1,567 2020 252.6 233.6 197.9 123.2 1,088 2021 205.7 215.6 135.9 815 2022 248.7 179.1 478 Total $ 1,628.7 Casualty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 3.4 15.7 42.3 64.4 91.8 113.5 126.0 137.9 144.2 151.9 2014 2.5 13.6 37.4 59.6 85.4 105.9 123.4 133.0 144.7 2015 3.3 17.5 37.8 64.7 88.4 107.3 121.4 135.1 2016 8.9 32.9 62.9 94.8 124.6 145.3 174.6 2017 8.7 30.2 58.5 96.5 115.7 147.7 2018 7.1 33.2 73.0 103.8 130.4 2019 9.1 36.2 60.9 82.1 2020 9.1 27.6 44.1 2021 7.8 37.1 2022 9.4 Total $ 1,057.1 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 571.6 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 571.6 Specialty Reinsurance Incurred Claims, IBNR and Loss Adjustment Expenses, Net of Reinsurance As at December 31, 2022 Total of IBNR Plus Expected Development on Reported Claims Cumulative Number of Reported Claims For the Years Ended December 31, Unaudited Prior Years Accident 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 $ (in millions) 2013 140.5 135.7 127.7 116.3 115.7 111.9 111.6 108.3 104.8 98.1 — 579 2014 149.5 137.5 129.5 120.8 123.6 122.2 118.0 116.6 105.4 — 622 2015 163.2 166.4 161.1 155.9 154.5 150.0 150.0 132.5 — 774 2016 235.8 236.6 234.6 227.6 222.6 218.8 197.6 — 938 2017 375.4 388.4 372.1 361.1 364.2 325.9 — 1,336 2018 392.7 391.9 390.3 419.5 342.1 — 1,403 2019 470.3 493.4 397.4 423.6 — 1,537 2020 412.8 600.0 374.1 53.1 1,470 2021 156.6 151.6 55.8 1,276 2022 193.9 107.9 969 Total $ 2,344.8 Specialty Reinsurance Cumulative Paid Claims and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Unaudited Prior Years Accident Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 ($ in millions) 2013 24.3 68.7 84.4 91.4 98.4 98.4 99.3 99.0 98.1 98.1 2014 16.2 55.2 79.8 87.8 98.0 100.9 102.5 104.4 105.4 2015 17.3 55.2 102.5 119.9 128.7 131.7 131.7 132.5 2016 58.2 149.5 163.9 181.7 191.8 201.8 197.6 2017 94.1 237.4 268.9 303.8 314.4 325.9 2018 26.7 279.0 312.2 328.5 342.1 2019 272.5 379.6 398.8 423.6 2020 212.8 269.6 290.4 2021 28.2 53.2 2022 25.8 Total $ 1,994.6 All outstanding liabilities for 2013 and subsequent years, net of reinsurance 350.2 All outstanding liabilities before 2013, net of reinsurance — Liabilities for claims and claim adjustment expenses, net of reinsurance $ 350.2
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability	Reconciliation of Incurred and Paid Claims Development to total Provision for Losses and LAE Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 ($ in millions) Net outstanding liabilities: Insurance lines - Property insurance lines 259.0 289.3 - Casualty insurance lines 457.3 725.6 - Marine, aviation and energy insurance lines 163.7 427.9 - Financial and professional insurance lines 671.9 808.7 Total insurance lines 1,551.9 2,251.5 Reinsurance lines - Property catastrophe and other property reinsurance 677.9 784.9 - Casualty reinsurance 571.6 975.3 - Specialty reinsurance 350.2 472.3 Total reinsurance lines 1,599.7 2,232.5 Net loss and LAE 3,151.6 4,484.0 Reinsurance recoverable on unpaid losses: Insurance lines 2,907.8 2,117.4 Reinsurance lines 1,989.9 1,180.7 Total reinsurance recoverable on unpaid losses 4,897.7 3,298.1 Deferred gain on retroactive contracts 42.7 58.3 Unallocated claims incurred 41.4 56.6 Other reinsurance balances recoverable (1) (429.3) (286.4) Carbon syndicate reserves 5.2 1.0 Other 1.6 0.2 (338.4) (170.3) Provision for losses and LAE at the end of the year 7,710.9 7,611.8 ________________ (1)
Short-duration Insurance Contracts, Schedule of Historical Claims Duration	Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance Years 1 2 3 4 5 6 7 8 9 10 Insurance 16.6 % 27.0 % 19.4 % 13.6 % 8.3 % 9.6 % 6.0 % 4.7 % 2.2 % 2.6 % Reinsurance 20.5 % 33.7 % 15.7 % 10.1 % 7.8 % 5.9 % 4.3 % 2.7 % 2.3 % 1.9 %

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Summary of Total Income Tax	Total income tax (benefit)/expense for the twelve months ended December 31, 2022, 2021 and 2020 was allocated as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Income tax (benefit)/expense allocated to net income $ (78.1) $ 5.3 $ 18.4 Income tax (benefit)/expense allocated to other comprehensive income (23.9) 0.3 0.5 Total income tax (benefit)/expense $ (102.0) $ 5.6 $ 18.9
Schedule of Income Tax by Taxing Authority	(Loss)/income from operations before income taxes and income tax expense/(benefit) attributable to that (loss)/income for the twelve months ended December 31, 2022, 2021 and 2020 is provided in the tables below: Twelve Months Ended December 31, 2022 (Loss)/income Current tax Deferred tax Total income tax ($ in millions) Bermuda $ (103.3) $ — $ — $ — U.S. (1) (2) 34.8 14.8 (102.9) (88.1) U.K. (3) 62.4 7.0 — 7.0 Other (4) (20.9) 4.7 (1.7) 3.0 Total $ (27.0) $ 26.5 $ (104.6) $ (78.1) Twelve Months Ended December 31, 2021 Income/(loss) Current tax Deferred tax Total income tax ($ in millions) Bermuda $ 22.9 $ — $ — $ — U.S. 5.0 5.8 — 5.8 U.K. 75.1 — (0.3) (0.3) Other (67.9) 2.7 (2.9) (0.2) Total $ 35.1 $ 8.5 $ (3.2) $ 5.3 Twelve Months Ended December 31, 2020 (Loss)/income Current tax Deferred tax Total income tax ($ in millions) Bermuda $ (81.5) $ — $ — $ — U.S 19.7 8.9 — 8.9 U.K. 11.0 0.1 — 0.1 Other 12.8 10.3 (0.9) 9.4 Total $ (38.0) $ 19.3 $ (0.9) $ 18.4
Income Tax Reconciliation	The reconciliation between the income tax (benefit)/expense and the amount that would result from applying the statutory rate for the Company for the twelve months ended December 31, 2022, 2021 and 2020 is provided in the table below: Twelve Months Ended December 31, 2022 2021 2020 Income Tax Reconciliation ($ in millions) Income tax benefit at statutory tax rate of zero percent $ — $ — $ — Overseas statutory tax rates differential 16.8 (0.9) (3.8) Base erosion and anti-abuse tax (BEAT) expense 2.3 6.1 4.3 Prior year adjustments (1) (2.9) 0.5 (25.0) Change in valuation allowance (2) (98.9) 9.6 40.8 Impact of unrecognized tax benefits (3) — — — Australian non-resident withholding tax 1.5 0.6 1.0 Foreign exchange (0.3) (1.5) 0.2 Non-deductible expenses 2.4 2.4 4.7 Impact of changes in statutory tax rates (4) (5.7) (11.5) (3.8) Tax effect of OCI in income statement 6.7 — — Total income tax (benefit)/expense $ (78.1) $ 5.3 $ 18.4 ________________ (1) The submission dates for filing income tax returns for the Company’s U.S. and U.K. operating subsidiaries are after the submission date of this report. Accordingly, the final tax liabilities may differ from the estimated income tax expense included in this report and may result in prior year adjustments being reported. The prior period adjustments for the twelve months ended December 31, 2022 predominantly relate to the determination of the results of the branches of the U.K. operating subsidiaries. The prior period adjustments for the twelve months ended December 31, 2021 and 2020 predominantly relate to the determination of results in the U.K. (2) The 2022 valuation allowance movement includes nil relating to U.K deferred tax assets in U.K. operating subsidiaries, $4.8 million decrease relating to deferred tax assets in the branches of the U.K. and Bermuda operating subsidiaries, and $94.1 million decrease from U.S. operations. The decrease in valuation allowance relating to our U.S. operations is driven by a change in judgment about the recoverability of deferred tax assets in the U.S. operating subsidiaries. We have concluded that the deferred tax assets of our U.S. operating subsidiaries will more likely than not be fully utilized over time, and therefore the previously recognized valuation allowance in relation to U.S. operating subsidiaries has been reversed. (3)
Tax Effects of Deferred Tax Assets and Deferred Tax Liabilities	The tax effects of temporary differences and carryforwards that give rise to deferred tax assets and deferred tax liabilities are presented in the following table as at December 31, 2022 and 2021: As at December 31, 2022 2021 ($ in millions) Deferred tax assets: Operating loss carryforwards 167.6 170.2 Capital loss carryforwards 6.7 0.3 Insurance reserves: Losses and loss adjustment expenses 28.3 16.7 Unrealized losses on investments 20.6 — Accrued expenses 6.1 4.6 Foreign tax credit carryforwards 19.8 20.2 Insurance reserves: Unearned premiums 36.0 28.3 Intangible assets 0.7 — Office properties and equipment 14.2 15.1 Operating lease liabilities 18.5 19.2 Other temporary differences 3.7 2.9 Total deferred tax assets 322.2 277.5 Less valuation allowance (145.7) (225.9) Deferred tax assets, net of valuation allowance $ 176.5 $ 51.6 Deferred tax liabilities: Investments — (2.5) Intangible assets — (2.8) Deferred acquisition costs (37.0) (28.6) Right-of-use operating lease assets (13.7) (10.6) Insurance reserves: Losses and loss adjustment expenses (0.2) (8.3) Other temporary differences (6.4) (1.6) Total deferred tax (liabilities) (57.3) (54.4) Net deferred tax assets/(liabilities) $ 119.2 $ (2.8)

Capital Structure (Tables)

Capital Structure (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Summary of Authorized and Issued Share Capital	The following table provides a summary of the Company’s authorized and issued share capital as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2021 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2021 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 ________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. The following table provides a summary of the Company’s authorized and issued share capital as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2022 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2022 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 __________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares.

Statutory Requirements and Divi

Statutory Requirements and Dividends Restrictions (Tables)	6 Months Ended
	Jun. 30, 2023
Disclosure Statutory Requirements And Dividends Restrictions Summary Of Statutory Requirements And Dividends Restrictions [Abstract]
Summary of Statutory Requirements and Dividends Restrictions	Statutory Requirements and Dividends Restrictions As a holding company, the Company relies on dividends and other distributions from its Operating Subsidiaries to provide cash flow to meet ongoing cash requirements, including any future debt service payments and other expenses, and to pay dividends, if any, to our preference and ordinary shareholders. The Company must comply with the provisions of the Bermuda Companies Act 1981, as amended, (the “Companies Act”) regulating the payment of dividends and distributions. The ability of the Company’s Operating Subsidiaries to pay the Company dividends or other distributions is subject to the laws and regulations applicable to each jurisdiction, as well as the Operating Subsidiaries’ need to maintain capital requirements adequate to maintain their insurance and reinsurance operations and their financial strength ratings issued by independent rating agencies. The company law of England and Wales prohibits Aspen UK, AMAL or AUL from declaring a dividend to its shareholders unless it has “profits available for distribution”. The determination of whether a company has profits available for distribution is based on its accumulated realized profits and other distributable reserves less its accumulated realized losses. While the U.K. insurance regulatory laws impose no statutory restrictions on a general insurer’s ability to declare a dividend, the rules of the Prudential Regulation Authority (the “PRA”) require each insurance company within its jurisdiction to maintain its solvency margin at all times. Accordingly, Aspen UK, AMAL and AUL may not pay a dividend if the payment of such dividend would result in their SCR coverage ratio falling below certain levels. In addition, any future changes regarding regulatory requirements, including those described above, may restrict the ability of Aspen UK, AMAL and AUL to pay dividends in the future. As at December 31, 2022, Aspen UK had an accumulated balance of retained losses of approximately $467.4 million and AUL had an accumulated balance of retained losses of approximately £62.2 million. Aspen UK held a capital contribution reserve of $655.0 million as at December 31, 2022 which, under certain circumstances, could be distributable. Aspen Bermuda must comply with the provisions of the Companies Act and the Insurance Act regulating the payment of dividends and distributions. Aspen Bermuda may not in any financial year pay dividends which would exceed 25% of its total statutory capital and surplus, as shown on its statutory balance sheet in relation to the previous financial year, unless it files with the BMA a solvency affidavit at least seven days in advance of payment. As at December 31, 2022, 25% of Aspen Bermuda’s statutory capital and surplus amounted to $262.1 million. Aspen Bermuda must also obtain the prior approval of the BMA before reducing its total statutory capital as set out in its previous year’s financial statements by 15% or more. Under both North Dakota and Texas law, insurance companies may only pay dividends out of earned surplus as distinguished from contributed surplus. As such, Aspen Specialty and AAIC could not pay a dividend as at December 31, 2022 without prior regulatory approval. Actual and required statutory capital and surplus for the principal Operating Subsidiaries of the Company, excluding its Lloyd’s syndicate, as at December 31, 2022 and December 31, 2021 were estimated as follows: As at December 31, 2022 U.S. Bermuda U.K. ($ in millions) Required statutory capital and surplus $ 513.9 $ 536.7 $ 771.8 Actual statutory capital and surplus $ 838.6 $ 1,426.5 $ 802.5 As at December 31, 2021 U.S. Bermuda U.K. ($ in millions) Required statutory capital and surplus $ 561.2 $ 683.7 $ 800.7 Actual statutory capital and surplus $ 889.7 $ 1,141.0 $ 963.6 As the sole corporate member of our Lloyd’s Syndicate, AUL was required to hold capital at Lloyd’s of $968.7 million as at December 31, 2022, adjusting funding to meet this level on an annual basis in the following Q2 and not holding less than 90% of this amount at any time. As at December 31, 2022, AUL had capital at Lloyd’s of $1,045.9 million of which $479.6 million was provided as Funds at Lloyd’s by Aspen Bermuda. The Bermuda Monetary Authority is the group supervisor of the Company. The laws and regulations of Bermuda require that the Company maintain a minimum amount of group statutory capital and surplus based on the enhanced capital requirement using the group standardized risk-based capital model of the Bermuda Monetary Authority. The Company is also subject to an early-warning level based on 120% of the enhanced capital requirement which may trigger additional reporting requirements or other enhanced oversight. The statutory capital requirements of the Company’s Operating Subsidiaries are set out above. To the extent that these requirements are met, the Company do not anticipate any dividend restrictions arising as a result of the Company’s enhanced capital requirement.

Dividends (Tables)

Dividends (Tables)	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Summary of Declared Dividends	Dividends. On March 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 April 1, 2023 March 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 April 1, 2023 March 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 April 1, 2023 March 15, 2023 ________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share. Dividends . On June 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 July 1, 2023 June 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 July 1, 2023 June 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 July 1, 2023 June 15, 2023 __________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000 th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share.

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	6 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Intangible Assets	The following table provides a summary of the Company’s intangible assets for the twelve months ended December 31, 2022 and 2021: Twelve Months Ended December 31, 2022 Beginning of the Year Additions/(Disposals) Amortization Impairment End of the Year ($ in millions) Intangible Assets Trademarks $ 1.3 $ — $ (0.1) $ — $ 1.2 Insurance Licenses 16.7 — — — 16.7 Goodwill 3.9 — — — 3.9 Total $ 21.9 $ — $ (0.1) $ — $ 21.8 Twelve Months Ended December 31, 2021 Beginning of the Year Additions/(Disposals) Amortization Impairment End of the Year ($ in millions) Intangible Assets Trademarks $ 1.6 $ — $ (0.3) $ — $ 1.3 Agency Relationships 0.6 — (0.6) — — Insurance Licenses 16.7 — — — 16.7 Goodwill 3.9 — — — 3.9 Total $ 22.8 $ — $ (0.9) $ — $ 21.9

Operating Leases (Tables)

Operating Leases (Tables)	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Lease, Cost	Operating lease charge. The following table summarizes the operating lease charge for the twelve months ended December 31, 2022 and 2021: For the Twelve Months Ended December 31, 2022 December 31, 2021 ($ in millions) Amortization charge on right-of-use operating leased assets $ 10.1 $ 12.0 Interest on operating lease liabilities 5.4 5.5 Operating lease charge $ 15.5 $ 17.5
Lessee, Operating Lease, Liability	The following table summarizes the maturity of lease liabilities under non-cancellable leases as of December 31, 2022 and 2021: December 31, 2022 December 31, 2021 ($ in millions) Operating leases — maturities 2022 $ — $ 17.0 2023 15.4 17.0 2024 15.2 16.5 2025 14.9 16.1 2026 14.1 15.3 2027 12.6 13.8 Later years 47.2 48.0 Total minimum lease payments $ 119.4 $ 143.7 Less imputed interest (23.9) (28.5) Total lease liabilities $ 95.5 $ 115.2
Summary of Other Lease Information	The following table summarizes the cash flows on operating leases for the twelve months ended December 31, 2022 and 2021, and other supplemental information: For the Twelve Months Ended December 31, 2022 December 31, 2021 ($ in millions) Cash paid for amounts included in the measurement of lease liabilities - Operating cash outflow from operating leases $ (15.5) $ (17.5) Right-of-use assets obtained in exchange for lease obligations - Operating leases $ 1.9 $ 23.9 Reduction to Right-of-use assets resulting from reductions to lease obligations - Operating leases $ 7.0 $ 2.3 Weighted Averages - Operating leases, remaining lease terms (years) 8.1 8.8 - Operating leases, average discount rate 5.0 % 5.0 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Company's Restricted Assets	The following table details the forms and value of Company’s material restricted assets as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 707.1 $ 891.3 Third party 2,817.7 3,099.7 Letters of credit / guarantees (1) 471.3 539.8 Total restricted assets (excluding illiquid assets) 3,996.1 4,530.8 Other investments — illiquid assets 221.3 151.3 Total restricted assets and illiquid assets $ 4,217.4 $ 4,682.1 Total as percent of cash and invested assets (2) 59.4 % 59.7 % ________________ (1) As at December 31, 2022, the Company had pledged funds of $471.3 million (December 31, 2021 — $539.8 million) as collateral for the secured letters of credit. (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. The following table details the forms and value of Company’s material restricted assets as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 617.0 $ 707.1 Third party 2,773.8 2,817.7 Letters of credit / guarantees (1) 266.5 471.3 Total restricted assets (excluding illiquid assets) 3,657.3 3,996.1 Other investments — illiquid assets 213.4 221.3 Total restricted assets and illiquid assets $ 3,870.7 $ 4,217.4 Total as percent of cash and investable assets (2) 52.6 % 59.4 % __________________ (1) As at June 30, 2023, the Company had pledged funds as collateral for the secured letters of credit of $266.5 million (December 31, 2022 — $471.3 million). (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased.

Concentration of Credit Risk (T

Concentration of Credit Risk (Tables)	6 Months Ended
	Jun. 30, 2023
Risks and Uncertainties [Abstract]
Schedule Of Gross Written Premium From Major Brokers	The following table shows the largest brokers that the Company transacted business within the three years ended December 31, 2022 and the proportion of gross written premiums from each of those brokers. Twelve Months Ended December 31, 2022 2021 2020 (in percentages) Aon Corporation 22.3 % 17.3 % 15.8 % Marsh & McLennan Companies, Inc. 21.8 17.5 15.4 Willis Group Holdings, Ltd. 8.0 9.6 10.4 Other brokers/non-broker sources (1) 47.9 55.6 58.4 Total 100.0 % 100.0 % 100.0 % Gross written premiums ($ millions) $ 4,338.7 $ 3,938.4 $ 3,698.5 __________________ (1)

Reclassifications from Accumu_3

Reclassifications from Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income Reclassification	The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the twelve months ended December 31, 2022 and 2021: Amount Reclassified from AOCI Details about the AOCI Components Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Affected Line Item in the ($ in millions) Available for sale: Realized (gains) on sale of securities and cash and cash equivalents $ (3.9) $ (24.8) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 58.9 4.4 Realized and unrealized investment losses 55.0 (20.4) Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 55.0 $ (20.4) Net income/(loss) Realized derivatives: Net realized gains on settled derivatives 15.4 (6.2) General, administrative and corporate expenses Tax on settled derivatives — — Income tax (expense)/benefit $ 15.4 $ (6.2) Net income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 70.4 $ (26.6) Net income/(loss) The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the six months ended June 30, 2023 and 2022: Amount Reclassified from AOCI Details about the AOCI Components Six Months Ended June 30, 2023 Six Months Ended June 30, 2022 Affected Line Item in the ($ in millions) Available for sale: Realized gains on sale of securities and cash and cash equivalents $ (0.4) $ (2.3) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 7.2 30.1 Realized and unrealized investment losses 6.8 27.8 Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 6.8 $ 27.8 Net income/(loss) Realized derivatives: Net realized loss on settled derivatives (4.3) (6.4) General, administrative and corporate expenses Tax on settled derivatives — 0.6 Income tax (expense)/benefit $ (4.3) $ (5.8) Net Income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 2.5 $ 22.0 Net income/(loss)

Credit Facility and Short-term

Credit Facility and Short-term Debt (Tables)	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Summary of Contractual Obligations Under Short-term Debts	The following table summarizes our contractual obligations under short-term debt as at December 31, 2022. Payments Due By Period Contractual Basis Less than 1 year Total ($ in millions) Short-term Debt Obligations $ 300.0 $ 300.0 The Senior Notes obligation disclosed above does not include the $14.3 million annual interest payable associated with the Senior Notes.

Credit Losses (Tables)

Credit Losses (Tables)	6 Months Ended
	Jun. 30, 2023
Credit Loss [Abstract]
Reinsurance Recoverable, Allowance for Credit Loss	The following tables summarize the Company’s allowance for expected credit losses for the twelve months ended December 31, 2022 in investments, reinsurance recoverables and receivables following the adoption of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326) ”: Twelve Months Ended December 31, 2022 ($ in millions) Investments Reinsurance Recoverables Receivables Total Opening value as at January 1, 2022 $ 2.7 $ 3.3 $ 30.2 $ 36.2 Movement of the allowance for credit losses during the year 5.0 0.4 (5.2) 0.2 Closing value as at December 31, 2022 $ 7.7 $ 3.7 $ 25.0 $ 36.4 Twelve Months Ended December 31, 2021 ($ in millions) Investments Reinsurance Recoverables Receivables Total Opening value as at January 1, 2021 $ 0.2 $ 3.8 $ 34.0 $ 38.0 Movement of the allowance for credit losses during the year 2.5 (0.5) (3.8) (1.8) Closing value as at December 31, 2021 $ 2.7 $ 3.3 $ 30.2 $ 36.2

Segment Reporting (Tables)_2

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Summary of gross and net written and earned premiums, underwriting results, ratios and reserves for each of Company's business segments	The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for the twelve months ended December 31, 2022, 2021 and 2020: Twelve Months Ended December 31, 2022 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,807.0 $ 2,531.7 $ 4,338.7 Net written premiums 1,426.4 1,469.6 2,896.0 Gross earned premiums 1,617.2 2,370.8 3,988.0 Net earned premiums 1,251.8 1,436.9 2,688.7 Underwriting Expenses Losses and loss adjustment expenses 770.3 909.7 1,680.0 Acquisition costs 252.4 179.4 431.8 General and administrative expenses 142.5 244.0 386.5 Underwriting income 86.6 103.8 190.4 Corporate expenses (71.7) Non-operating expenses (1) (36.0) Net investment income 188.1 Realized and unrealized investment gains 5.0 Realized and unrealized investment losses (182.6) Change in fair value of derivatives (80.5) Interest expense (43.7) Net realized and unrealized foreign exchange gains 15.9 Other income 8.2 Other expenses (20.1) (Loss) before income taxes (27.0) Income tax benefit 78.1 Net income $ 51.1 Net reserves for loss and loss adjustment expenses $ 1,360.7 $ 1,452.5 $ 2,813.2 Ratios Loss ratio 61.5 % 63.3 % 62.5 % Acquisition cost ratio 20.2 12.5 16.1 General and administrative expense ratio 11.4 17.0 14.4 Expense ratio 31.6 29.5 30.5 Combined ratio 93.1 % 92.8 % 93.0 % ________________ (1) Non-operating expenses includes $32.7 million in relation to fixed assets written off, $10.0 million of severance, consulting and professional services in relation to non-recurring projects and other costs, offset by $6.7 million of write backs related to leased office space. Twelve Months Ended December 31, 2021 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,597.0 $ 2,341.4 $ 3,938.4 Net written premiums 1,199.0 1,388.7 2,587.7 Gross earned premiums 1,479.2 2,139.1 3,618.3 Net earned premiums 1,118.8 1,291.7 2,410.5 Underwriting Expenses Losses and loss adjustment expenses 705.2 988.1 1,693.3 Acquisition costs 221.6 192.5 414.1 General and administrative expenses 121.3 211.8 333.1 Underwriting income/(loss) 70.7 (100.7) (30.0) Corporate expenses (64.3) Non-operating expenses (1) (20.6) Net investment income 147.5 Realized and unrealized investment gains 56.2 Realized and unrealized investment losses (47.4) Change in fair value of derivatives (35.9) Interest expense (14.3) Net realized and unrealized foreign exchange gains 40.0 Other income 14.7 Other expenses (10.8) Income before income taxes 35.1 Income tax (expense) (5.3) Net income $ 29.8 Net reserves for loss and loss adjustment expenses $ 2,148.4 $ 2,165.3 $ 4,313.7 Ratios Loss ratio 63.0 % 76.5 % 70.2 % Acquisition cost ratio 19.8 14.9 17.2 General and administrative expense ratio 10.8 16.4 13.8 Expense ratio 30.6 31.3 31.0 Combined ratio 93.6 % 107.8 % 101.2 % ________________ (1) Non-operating expenses includes $19.3 million of costs related to consulting and professional services in relation to non-recurring projects and other costs, $0.4 million of impairment charges related to lease assets as a result of exiting certain office space and $0.9 million of amortization of intangible assets and other non-operating expenses. Twelve Months Ended December 31, 2020 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 1,656.4 $ 2,042.1 $ 3,698.5 Net written premiums 1,297.7 1,280.1 2,577.8 Gross earned premiums 1,612.0 2,026.4 3,638.4 Net earned premiums 1,287.7 1,239.8 2,527.5 Underwriting Expenses Losses and loss adjustment expenses 958.6 882.2 1,840.8 Acquisition costs 246.0 219.7 465.7 General and administrative expenses 110.8 197.2 308.0 Underwriting (loss) (27.7) (59.3) (87.0) Corporate expenses (70.2) Non-operating expenses (1) (32.7) Net investment income 154.6 Realized and unrealized investment gains 98.5 Realized and unrealized investment losses (27.4) Change in fair value of derivatives (65.1) Interest expense (33.9) Net realized and unrealized foreign exchange (losses) (13.8) Other income 49.8 Other expenses (10.8) (Loss) before income taxes (38.0) Income tax (expense) (18.4) Net (loss) $ (56.4) Net reserves for loss and loss adjustment expenses $ 2,095.7 $ 1,874.4 $ 3,970.1 Ratios Loss ratio 74.4 % 71.1 % 72.8 % Acquisition cost ratio 19.1 17.7 18.4 General and administrative expense ratio 8.6 15.9 12.2 Expense ratio 27.7 33.6 30.6 Combined ratio 102.1 % 104.7 % 103.4 % ________________ (1) Non-operating expenses includes $18.2 million of expenses related to severance, retention and other costs, $12.9 million of impairment charges related to lease assets as a result of sub-leasing certain office space and $1.6 million of amortization of intangible assets and other non-operating expenses. The following tables provide a summary of gross and net written and earned premiums, underwriting income or loss, ratios and reserves for each of the Company’s business segments for six months ended June 30, 2023 and 2022: Six Months Ended June 30, 2023 Reinsurance Insurance Total ($ in millions) Underwriting Revenues Gross written premiums $ 875.7 $ 1,249.5 $ 2,125.2 Net written premiums 605.0 745.5 1,350.5 Net earned premiums 572.0 715.4 1,287.4 Underwriting Expenses Losses and loss adjustment expenses 297.2 419.9 717.1 Acquisition costs 105.7 87.2 192.9 General and administrative expenses 58.4 110.6 169.0 Underwriting income 110.7 97.7 208.4 Corporate and other expenses (1) (53.1) Non-operating expenses (10.6) Net investment income 129.4 Realized and unrealized investment gains 36.1 Realized and unrealized investment losses (18.1) Change in fair value of derivatives 19.6 Interest expense (42.9) Net realized and unrealized foreign exchange losses (13.7) Income before income taxes 255.1 Income tax (expense) (36.2) Net income $ 218.9 Net reserves for loss and loss adjustment expenses $ 1,441.2 $ 1,641.7 $ 3,082.9 Ratios Loss ratio 52.0 % 58.7 % 55.7 % Acquisition cost ratio 18.5 12.2 15.0 General and administrative expense ratio 10.2 15.5 13.1 Expense ratio 28.7 27.7 28.1 Combined ratio 80.7 % 86.4 % 83.8 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately. Six Months Ended June 30, 2022 Reinsurance Insurance Total ( $ in millions) Underwriting Revenues Gross written premiums $ 1,045.6 $ 1,305.7 $ 2,351.3 Net written premiums 783.7 722.4 1,506.1 Net earned premiums 600.8 726.4 1,327.2 Underwriting Expenses Losses and loss adjustment expenses 369.0 398.7 767.7 Acquisition costs 124.1 92.4 216.5 General and administrative expenses 69.7 116.8 186.5 Underwriting income 38.0 118.5 156.5 Corporate and other expenses (1) (37.5) Non-operating expenses (3.6) Net investment income 88.7 Realized and unrealized investment gains 2.5 Realized and unrealized investment losses (128.9) Realized loss on debt extinguishment — Change in fair value of loan notes issued by variable interest entities — Change in fair value of derivatives (84.9) Interest expense (9.1) Net realized and unrealized foreign exchange gains 75.2 Other income 2.9 Other expenses (8.7) Income before income taxes 53.1 Income tax (expense) (4.7) Net income $ 48.4 Net reserves for loss and loss adjustment expenses $ 1,190.4 $ 1,314.9 $ 2,505.3 Ratios Loss ratio 61.4 % 54.9 % 57.8 % Acquisition cost ratio 20.7 12.7 16.3 General and administrative expense ratio 11.6 16.1 14.1 Expense ratio 32.3 28.8 30.4 Combined ratio 93.7 % 83.7 % 88.2 % __________________ (1) Corporate and other operating expenses includes other income/expenses, which were previously presented separately.

Investments (Tables)_2

Investments (Tables)	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Investment Income	The following table summarizes investment income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Fixed income securities — Available for sale $ 95.6 $ 87.2 $ 106.5 Fixed income securities — Trading 57.0 30.2 32.8 Short-term investments — Available for sale 0.6 0.1 0.8 Short-term investments — Trading 0.1 — 0.5 Fixed term deposits (included in cash and cash equivalents) 6.6 0.7 6.4 Catastrophe bonds — Trading 0.3 0.9 1.4 Privately-held investments — Trading 24.3 18.2 20.9 Other investments, at fair value (1) 13.9 21.9 (2.0) Total 198.4 159.2 167.3 Investment expenses (10.3) (11.7) (12.7) Net investment income $ 188.1 $ 147.5 $ 154.6 ________________ (1) Other investments represents the Company’s investments in real estate funds and other special purpose vehicles. The movement in the year represents the change in fair value of the investment and has been included as part of our investment income. For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Fixed income securities — Available for sale $ 55.7 $ 44.5 Fixed income securities — Trading 47.8 18.9 Short-term investments — Available for sale 1.6 — Short-term investments — Trading 0.1 — Fixed term deposits (included in cash and cash equivalents) 17.3 0.5 Catastrophe bonds — Trading 1.1 0.1 Privately-held investments — Trading 21.5 8.8 Other investments, at fair value (1) (10.4) 20.7 Total 134.7 93.5 Investment expenses (5.3) (4.8) Net investment income $ 129.4 $ 88.7 __________________ (1)
Net Realized and Unrealized Investment Gains and Losses and Change in Unrealized Gains and Losses on Investments	The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the twelve months ended December 31, 2022, 2021 and 2020: For the Twelve Months Ended December 31, 2022 December 31, 2021 December 31, 2020 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 2.9 $ 22.7 $ 68.8 Fixed income securities — gross realized (losses) (58.4) (3.6) (1.8) Short-term investments — gross realized gains 1.0 2.0 0.5 Short-term investments — gross realized (losses) (0.5) (0.8) (0.4) Net change in expected credit (losses)/gains (5.0) (2.5) 0.4 Trading: Fixed income securities — gross realized gains 0.2 12.2 18.2 Fixed income securities — gross realized (losses) (1.8) (2.0) (3.8) Short-term investments — gross realized gains — 0.1 0.2 Short-term investments — gross realized (losses) — (0.3) (0.3) Privately-held investments — gross realized gains 0.7 0.6 — Privately-held investments — gross realized (losses) (0.1) (13.8) — Privately-held investments — net unrealized (losses)/gains (2.5) 18.1 (20.4) Catastrophe bonds — net unrealized gains/(losses) 0.2 (0.8) — Fixed income securities — net unrealized (losses) (113.9) (23.4) — Investments — equity method: Gross realized and unrealized gains/(losses) in MVI — 0.1 (0.4) Gross unrealized (losses)/gains in Multi-Line Reinsurer (0.4) 0.2 — Gross realized and unrealized (losses)/gains in Digital Risk — — (0.3) Gross realized gain on sale of Bene — — 1.8 Gross realized gain on sale of Crop Re — — 8.6 Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations $ (177.6) $ 8.8 $ 71.1 Change in available for sale net unrealized (losses)/gains: Fixed income securities (391.7) (157.6) 108.5 Income tax benefit/(expense) 23.9 (0.3) (0.5) Total change in net unrealized (losses)/gains, net of taxes recorded in other comprehensive income $ (367.8) $ (157.9) $ 108.0 The following table summarizes the net realized and unrealized investment gains and losses recorded in the consolidated statement of operations and the change in unrealized gains and losses on investments recorded in other comprehensive income for the six months ended June 30, 2023 and 2022: For the Six Months Ended June 30, 2023 June 30, 2022 ($ in millions) Available for sale: Fixed income securities — gross realized gains $ 0.4 $ 1.4 Fixed income securities — gross realized (losses) (6.9) (29.9) Short-term investments — gross realized (losses) (0.2) — Cash and cash equivalents — gross realized gains 0.1 0.9 Cash and cash equivalents — gross realized (losses) (0.1) (0.2) Net change in expected credit gains/(losses) 3.7 (7.7) Trading: Fixed income securities — gross realized gains 0.3 — Fixed income securities — gross realized (losses) (1.1) (0.2) Short-term investments — gross realized gains 0.1 — Short-term investments — gross realized (losses) (0.2) — Privately-held investments — gross realized gains 0.1 0.2 Privately-held investments — net unrealized (losses) (9.0) (1.3) Catastrophe bonds — net unrealized (losses) (0.6) (0.1) Fixed income securities — net unrealized gains/(losses) 31.0 (89.6) Investments — equity method: Net change in realized and unrealized gains in Multi-Line Reinsurer 0.4 0.1 Total net realized and unrealized investment gains/(losses) recorded in the consolidated statement of operations $ 18.0 $ (126.4) Change in available for sale net unrealized gains/(losses): Fixed income securities gains/(losses) 12.3 (316.0) Income tax (expense)/benefit (1.6) 29.5 Total change in net unrealized gains/(losses), net of taxes recorded in other comprehensive income $ 10.7 $ (286.5)
Cost or Amortized Cost, Unrealized and Realized Gains and Losses and Estimated Fair Value of Available for Sale Investments	The following tables present the cost or amortized cost, gross unrealized gains and losses and estimated fair market value of available for sale investments in fixed income securities and short-term investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6 __________________ (1) For the twelve months ended December 31, 2022, there was an increase in the CECL allowance on available-for-sale investments of $5.0 million (December 31, 2021 — $2.5 million decrease). As at December 31, 2021 Cost or Gross Gross Allowance Fair Market ($ in millions) U.S. government $ 1,066.2 $ 24.0 $ (5.9) $ — $ 1,084.3 U.S. agency 20.7 0.8 — — 21.5 Municipal 81.2 2.0 (0.5) (0.1) 82.6 Corporate 2,176.1 47.5 (13.0) (2.3) 2,208.3 Non-U.S. government-backed corporate 138.5 0.2 (1.9) — 136.8 Non-U.S. government 250.8 1.4 (1.2) (0.3) 250.7 Asset-backed 0.5 — — — 0.5 Non-agency commercial mortgage-backed 6.6 0.3 — — 6.9 Agency mortgage-backed 1,082.9 19.1 (12.0) — 1,090.0 Total fixed income securities — Available for sale 4,823.5 95.3 (34.5) (2.7) 4,881.6 Total short-term investments — Available for sale 10.1 — — — 10.1 Total $ 4,833.6 $ 95.3 $ (34.5) $ (2.7) $ 4,891.7 As at June 30, 2023 Cost or Gross Gross Allowance for Credit Losses (1) Fair Market ($ in millions) U.S. government $ 1,064.9 $ — $ (51.1) $ — $ 1,013.8 U.S. agency 8.6 — (0.4) — 8.2 Municipal 159.0 — (8.8) (0.7) 149.5 Corporate 2,031.9 2.4 (155.2) (3.2) 1,875.9 Non-U.S. government-backed corporate 119.6 — (8.7) — 110.9 Non-U.S. government 281.3 — (12.0) (0.1) 269.2 Non-agency commercial mortgage-backed 6.6 — (0.9) — 5.7 Agency mortgage-backed 559.3 — (84.3) — 475.0 Total fixed income securities — Available for sale 4,231.2 2.4 (321.4) (4.0) 3,908.2 Total short-term investments — Available for sale 169.3 — — — 169.3 Total $ 4,400.5 $ 2.4 $ (321.4) $ (4.0) $ 4,077.5 __________________ (1) For the six months ended June 30, 2023, there was a decrease in the CECL allowance on available-for-sale investments of $3.7 million (December 31, 2022 — $5.0 million increase). As at December 31, 2022 Cost or Gross Gross Allowance for Credit Losses Fair Market ($ in millions) U.S. government $ 1,003.7 $ — $ (50.7) $ — $ 953.0 U.S. agency 9.2 — (0.4) — 8.8 Municipal 159.9 — (9.4) (1.0) 149.5 Corporate 2,016.9 3.5 (169.1) (6.3) 1,845.0 Non-U.S. government-backed corporate 119.4 — (8.8) (0.2) 110.4 Non-U.S. government 225.2 0.1 (11.5) (0.2) 213.6 Non-agency commercial mortgage-backed 6.6 — (1.0) — 5.6 Agency mortgage-backed 590.4 — (87.7) — 502.7 Total fixed income securities — Available for sale 4,131.3 3.6 (338.6) (7.7) 3,788.6 Total short-term investments — Available for sale 52.4 — (0.4) — 52.0 Total $ 4,183.7 $ 3.6 $ (339.0) $ (7.7) $ 3,840.6
Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Trading Investments in Fixed Income Maturities	The following tables present the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of trading investments in fixed income securities, short-term investments, equity securities, catastrophe bonds and privately-held investments as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 $ 0.6 $ (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Equity securities 6.6 — — 6.6 Short-term investments 25.6 — — 25.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7 As at December 31, 2021 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 115.9 $ 0.6 $ (0.2) $ 116.3 Municipal 3.9 0.1 — 4.0 Corporate 95.7 1.9 (0.8) 96.8 High yield loans 77.2 0.1 (0.4) 76.9 Non-U.S. government-backed corporate 13.3 — (0.2) 13.1 Non-U.S. government 34.9 — (0.4) 34.5 Asset-backed 784.3 3.3 (1.9) 785.7 Agency mortgage-backed 30.3 0.2 (0.3) 30.2 Total fixed income securities — Trading 1,155.5 6.2 (4.2) 1,157.5 Short-term investments — Trading 2.0 — — 2.0 Catastrophe bonds — Trading 5.3 — (1.9) 3.4 Privately-held investments — Trading Commercial mortgage loans $ 212.0 0.4 (0.9) $ 211.5 Middle market loans 66.9 — (1.5) 65.4 Asset-backed securities 26.8 — (0.2) 26.6 Equity securities 3.5 0.1 — 3.6 Total privately-held investments — Trading 309.2 0.5 (2.6) 307.1 Total Investments — Trading $ 1,472.0 $ 6.7 $ (8.7) $ 1,470.0 As at June 30, 2023 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 241.9 $ — $ (6.9) $ 235.0 Municipal 3.4 — (0.3) 3.1 Corporate 176.9 0.3 (11.8) 165.4 High yield loans 86.1 1.2 (0.7) 86.6 Non-U.S. government-backed corporate 10.1 — (0.5) 9.6 Non-U.S. government 35.8 — (1.7) 34.1 Asset-backed 975.2 1.0 (51.6) 924.6 Agency mortgage-backed 23.3 — (3.2) 20.1 Total fixed income securities — Trading 1,552.7 2.5 (76.7) 1,478.5 Short-term investments — Trading 11.0 — — 11.0 Catastrophe bonds — Trading 2.4 — — 2.4 Privately-held investments — Trading Commercial mortgage loans $ 305.5 $ 1.3 $ (11.8) $ 295.0 Middle market loans 104.1 — (2.0) 102.1 Asset-backed securities 59.5 — (1.1) 58.4 Global corporate securities 14.9 — (0.1) 14.8 Equity securities 12.1 — — 12.1 Total privately-held investments — Trading 496.1 1.3 (15.0) 482.4 Total Investments — Trading $ 2,062.2 $ 3.8 $ (91.7) $ 1,974.3 As at December 31, 2022 Cost or Gross Gross Fair Market ($ in millions) Fixed Income Securities — Trading U.S. government $ 267.9 $ — $ (6.3) $ 261.6 Municipal 3.9 — (0.3) 3.6 Corporate 175.3 0.3 (13.5) 162.1 High yield loans 90.2 0.2 (2.1) 88.3 Non-U.S. government-backed corporate 12.2 — (0.6) 11.6 Non-U.S. government 32.2 — (1.8) 30.4 Asset-backed 970.3 0.2 (74.0) 896.5 Agency mortgage-backed 24.7 — (3.3) 21.4 Total fixed income securities — Trading 1,576.7 0.7 (101.9) 1,475.5 Short-term investments — Trading 6.3 — — 6.3 Catastrophe bonds — Trading 5.1 — (2.2) 2.9 Privately-held investments — Trading Commercial mortgage loans $ 312.6 0.6 (1.1) $ 312.1 Middle market loans 109.0 — (2.1) 106.9 Asset-backed securities 68.8 — (2.0) 66.8 Global corporate securities 15.1 — (0.1) 15.0 Short-term investments 25.6 — — 25.6 Equity securities 6.6 — — 6.6 Total privately-held investments — Trading 537.7 0.6 (5.3) 533.0 Total Investments — Trading $ 2,125.8 $ 1.3 $ (109.4) $ 2,017.7
Schedule of Commercial Mortgage and Middle Market Loans	The following table presents the type of commercial mortgage loans and geographic region as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 115.3 36.9 101.6 48.1 Hotels 108.0 34.6 68.8 32.5 Office building 42.1 13.5 33.9 16.0 Other commercial 41.4 13.3 7.2 3.4 Retail 3.3 1.1 — — Industrial 2.0 0.6 — — Total commercial mortgage loans $ 312.1 100 % 211.5 100 % Geographic Region U.S. 269.8 86.4 183.7 86.9 International 42.3 13.6 27.8 13.1 Total commercial mortgage loans $ 312.1 100 % 211.5 100 % As at December 31, 2022 As at December 31, 2021 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 19.8 18.5 20.9 32.0 Financials 53.1 49.7 6.1 9.3 Industrials 18.7 17.5 18.7 28.5 Consumer discretionary 4.9 4.6 4.3 6.6 Energy 5.7 5.3 5.6 8.6 Consumer staples — — 4.9 7.5 Information technology 4.7 4.4 4.9 7.5 Total middle market mortgage loans $ 106.9 100 % $ 65.4 100 % Geographic Region U.S. 64.1 59.9 56.2 85.9 International 42.8 40.1 9.2 14.1 Total middle market loans $ 106.9 100 % $ 65.4 100 % As at June 30, 2023 As at December 31, 2022 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Property type Apartment 107.8 36.6 115.3 36.9 Hotels 98.1 33.3 108.0 34.6 Office building 45.9 15.5 42.1 13.5 Other commercial 37.9 12.8 41.4 13.3 Retail 3.3 1.1 3.3 1.1 Industrial 2.0 0.7 2.0 0.6 Total commercial mortgage loans $ 295.0 100 % 312.1 100 % Geographic Region U.S. 263.6 89.4 269.8 86.4 International 31.4 10.6 42.3 13.6 Total commercial mortgage loans $ 295.0 100 % 312.1 100 % As at June 30, 2023 As at December 31, 2022 Net Carrying Value Percentage of Total Net Carrying Value Percentage of Total ($ millions) (%) ($ millions) (%) Industry type Materials 20.0 19.6 19.8 18.5 Financials 48.3 47.3 53.1 49.7 Industrials 18.6 18.2 18.7 17.5 Consumer discretionary 4.9 4.8 4.9 4.6 Energy 5.6 5.5 5.7 5.3 Information technology 4.7 4.6 4.7 4.4 Total middle market mortgage loans $ 102.1 100 % $ 106.9 100 % Geographic Region U.S. 59.4 58.2 64.1 59.9 International 42.7 41.8 42.8 40.1 Total middle market loans $ 102.1 100 % $ 106.9 100 %
Credit Quality Indicators of Commercial Mortgage and Middle Market Loans	A loan-to-value ratio in excess of 100% indicates the unpaid loan amount exceeds the underlying collateral. The following table represents the loan-to-value ratio of the commercial mortgage loan portfolio as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 41.1 $ — 50% to 60% 248.3 131.2 61% to 70% 22.7 80.3 Commercial mortgage loans $ 312.1 $ 211.5 As at December 31, 2022 As at December 31, 2021 (in millions) Less than 50% $ 63.5 $ 11.0 50% to 60% 16.4 9.2 61% to 70% 27.0 15.8 71% to 80% — 5.6 81% to 100% — 12.0 Greater than 100% — 11.8 Middle market loans $ 106.9 $ 65.4 As at June 30, 2023 As at December 31, 2022 (in millions) Less than 50% $ 47.5 $ 41.1 50% to 60% 227.3 248.3 61% to 70% 20.2 22.7 Commercial mortgage loans $ 295.0 $ 312.1 As at June 30, 2023 As at December 31, 2022 (in millions) Less than 50% $ 63.5 $ 63.5 50% to 60% 23.3 16.4 61% to 70% 15.3 27.0 Middle market loans $ 102.1 $ 106.9
Debt Service and Fixed Charge Coverage Ratios	The following table represents the debt-service coverage ratio of the commercial mortgage loan portfolio, excluding those that are non-performing and construction loans which are still under development, as at December 31, 2022 and December 31, 2021: As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 106.1 $ 66.3 1.00 - 1.20x 186.1 62.4 Less than 1.00x — 18.8 Commercial mortgage loans (1) $ 292.2 $ 147.5 __________________ (1) As at December 31, 2022 As at December 31, 2021 (in millions) Greater than 1.20x $ 95.2 $ 25.8 1.00 - 1.20x 3.8 22.8 Less than 1.00x 7.9 16.8 Middle market loans $ 106.9 $ 65.4 As at June 30, 2023 As at December 31, 2022 (in millions) Greater than 1.20x $ 112.3 $ 106.1 1.00 - 1.20x 182.7 186.1 Less than 1.00x — — Commercial mortgage loans (1) $ 295.0 $ 292.2 ________________ (1) As at June 30, 2023, we have non-performing loans of $Nil (December 31, 2022 — $Nil) and construction loans of $Nil (December 31, 2022 — $19.9 million) which only generate income when the construction is completed. As no income is currently being generated on these loans, they are not included in the table above. The total value of commercial mortgage loans is $295.0 million as at June 30, 2023 (December 31, 2022 — $312.1 million). As at June 30, 2023 As at December 31, 2022 (in millions) Greater than 1.20x $ 78.9 $ 95.2 1.00 - 1.20x 3.8 3.8 Less than 1.00x 19.4 7.9 Middle market loans $ 102.1 $ 106.9
Other Investments	The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the twelve months ended December 31, 2022 and 2021: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Distribution received — — — — Unrealized (loss)/gain for the twelve months to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investment as at December 31, 2022 0.8 5.2 0.2 6.2 Opening undistributed value of investment as at January 1, 2021 $ — $ 0.5 $ 0.4 $ 0.9 Investment in the period 0.4 2.5 0.3 3.2 Distribution received — — (0.5) (0.5) Unrealized gain for the twelve months to December 31, 2021 0.1 0.2 — 0.3 Closing value of investments at December 31, 2021 $ 0.5 $ 3.2 $ 0.2 $ 3.9 The table below shows the Company’s investments in MVI, Multi-Line Reinsurer and Digital Re for the six months ended June 30, 2023 and the twelve months ended December 31, 2022: MVI Multi-Line Reinsurer Digital Re Total ($ in millions) Opening undistributed value of investment as at January 1, 2023 $ 0.8 $ 5.2 $ 0.2 $ 6.2 Investment in the period — 0.4 — 0.4 Unrealized gain for the period to June 30, 2023 — 0.4 — 0.4 Closing value of investment as at June 30, 2023 0.8 6.0 0.2 7.0 Opening undistributed value of investment as at January 1, 2022 $ 0.5 $ 3.2 $ 0.2 $ 3.9 Investment in the period 0.4 1.6 — 2.0 Unrealized (loss)/gain for the period to December 31, 2022 (0.1) 0.4 — 0.3 Closing value of investments at December 31, 2022 $ 0.8 $ 5.2 $ 0.2 $ 6.2
Summary of Fixed Maturities	Actual maturities may differ from contractual maturities because issuers of securities may have the right to call or prepay obligations with or without call or prepayment penalties. As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6 At December 31, 2021 Amortized Fair Market Average ($ in millions) Due one year or less $ 545.1 $ 549.0 AA- Due after one year through five years 2,057.2 2,087.5 AA- Due after five years through ten years 1,090.5 1,106.3 A+ Due after ten years 40.7 41.4 A- Total — Government and corporate 3,733.5 3,784.2 Non-agency commercial mortgage-backed 6.6 6.9 AA+ Agency mortgage-backed 1,082.9 1,090.0 AA+ Asset-backed 0.5 0.5 AAA Total fixed income securities — Available for sale $ 4,823.5 $ 4,881.6 As at June 30, 2023 Amortized Fair Market Average ($ in millions) Due one year or less $ 242.4 $ 236.5 AA Due after one year through five years 2,736.2 2,594.7 AA- Due after five years through ten years 684.9 595.2 A+ Due after ten years 1.8 1.1 BB Total — Government and corporate 3,665.3 3,427.5 Non-agency commercial mortgage-backed 6.6 5.7 AA+ Agency mortgage-backed 559.3 475.0 AA+ Total fixed income securities — Available for sale $ 4,231.2 $ 3,908.2 As at December 31, 2022 Amortized Fair Market Average ($ in millions) Due one year or less $ 179.1 $ 176.0 AA+ Due after one year through five years 2,526.9 2,385.7 AA- Due after five years through ten years 815.1 707.7 A+ Due after ten years 13.2 10.9 A- Total — Government and corporate 3,534.3 3,280.3 Non-agency commercial mortgage-backed 6.6 5.6 AA+ Agency mortgage-backed 590.4 502.7 AA+ Total fixed income securities — Available for sale $ 4,131.3 $ 3,788.6
Aggregate Fair Value and Gross Unrealized Loss by Type of Security	The following tables summarize, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Company’s available for sale portfolio as at December 31, 2022 and December 31, 2021: December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166 December 31, 2021 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 309.1 $ (4.0) $ 29.3 $ (1.9) $ 338.4 $ (5.9) 51 U.S. agency 6.1 — — — 6.1 — 5 Municipal 29.7 (0.5) — — 29.7 (0.5) 20 Corporate 804.6 (11.7) 23.6 (1.3) 828.2 (13.0) 400 Non-U.S. government-backed corporate 114.4 (1.9) — — 114.4 (1.9) 10 Non-U.S. government 181.8 (1.2) 3.1 — 184.9 (1.2) 35 Agency mortgage-backed 564.5 (11.6) 16.0 (0.4) 580.5 (12.0) 116 Total fixed income securities — Available for sale 2,010.2 (30.9) 72.0 (3.6) 2,082.2 (34.5) 637 Total short-term investments — Available for sale 4.4 — — — 4.4 — 7 Total $ 2,014.6 $ (30.9) $ 72.0 $ (3.6) $ 2,086.6 $ (34.5) 644 June 30, 2023 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 494.8 $ (12.8) $ 519.1 $ (38.3) $ 1,013.9 $ (51.1) 105 U.S. agency 7.0 (0.4) 1.1 — 8.1 (0.4) 4 Municipal 90.9 (3.7) 58.7 (5.1) 149.6 (8.8) 60 Corporate 467.4 (13.1) 1,254.7 (142.1) 1,722.1 (155.2) 727 Non-U.S. government-backed corporate 5.2 — 105.7 (8.7) 110.9 (8.7) 16 Non-U.S. government 80.1 (1.2) 182.2 (10.8) 262.3 (12.0) 61 Non-agency commercial mortgage-backed — — 5.6 (0.9) 5.6 (0.9) 1 Agency mortgage-backed 18.4 (1.3) 455.6 (83.0) 474.0 (84.3) 214 Total fixed income securities — Available for sale 1,163.8 (32.5) 2,582.7 (288.9) 3,746.5 (321.4) 1,188 Total short-term investments — Available for sale 11.8 — — — 11.8 — 5 Total $ 1,175.6 $ (32.5) $ 2,582.7 $ (288.9) $ 3,758.3 $ (321.4) 1,193 December 31, 2022 0-12 months Over 12 months Total Fair Gross Fair Gross Fair Gross Number of ($ in millions) U.S. government $ 741.1 $ (30.6) $ 203.4 $ (20.1) $ 944.5 $ (50.7) 118 U.S. agency 7.1 (0.4) 1.7 — 8.8 (0.4) 5 Municipal 133.1 (7.1) 16.4 (2.3) 149.5 (9.4) 59 Corporate 1,104.7 (77.6) 568.2 (91.5) 1,672.9 (169.1) 701 Non-U.S. government-backed corporate 11.3 (0.5) 99.0 (8.3) 110.3 (8.8) 16 Non-U.S. government 63.8 (2.9) 135.9 (8.6) 199.7 (11.5) 45 Non-agency commercial mortgage-backed securities 5.6 (1.0) — — 5.6 (1.0) 1 Agency mortgage-backed 202.8 (24.9) 299.1 (62.8) 501.9 (87.7) 220 Total fixed income securities — Available for sale 2,269.5 (145.0) 1,323.7 (193.6) 3,593.2 (338.6) 1,165 Total short-term investments — Available for sale 51.9 (0.4) — — 51.9 (0.4) 1 Total $ 2,321.4 $ (145.4) $ 1,323.7 $ (193.6) $ 3,645.1 $ (339.0) 1,166

Fair Value Measurements (Tabl_2

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Financial Assets Measured on Recurring Basis	The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at December 31, 2022 and December 31, 2021: As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Asset-backed — — — — Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Held for trading financial assets, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Privately-held investments trading, at fair value — — 533.0 533.0 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 56.2 — 56.2 Liabilities under derivative contracts — foreign exchange contracts — (3.2) — (3.2) Liabilities under derivative contracts — loss portfolio transfer (2) — — (31.7) (31.7) Total 1,428.7 3,949.6 501.3 6,100.9 ________________ (1) Other investments represents our investments in real estate and other special purpose vehicles and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. At December 31, 2021 Level 1 Level 2 Level 3 Total ($ in millions) Available for sale financial assets, at fair value U.S. government $ 1,084.3 $ — $ — $ 1,084.3 U.S. agency — 21.5 — 21.5 Municipal — 82.6 — 82.6 Corporate — 2,208.3 — 2,208.3 Non-U.S. government-backed corporate — 136.8 — 136.8 Non-U.S. government 164.4 86.3 — 250.7 Asset-backed — 0.5 — 0.5 Non-agency commercial mortgage-backed — 6.9 — 6.9 Agency mortgage-backed — 1,090.0 — 1,090.0 Total fixed income securities available for sale, at fair value 1,248.7 3,632.9 — 4,881.6 Short-term investments available for sale, at fair value 6.5 3.6 — 10.1 Held for trading financial assets, at fair value U.S. government 116.3 — — 116.3 Municipal — 4.0 — 4.0 Corporate — 96.8 — 96.8 Non-U.S. government-backed corporate — 13.1 — 13.1 High yield loans — 76.9 — 76.9 Non-U.S. government 11.9 22.6 — 34.5 Asset-backed — 785.7 — 785.7 Agency mortgage-backed — 30.2 — 30.2 Total fixed income securities trading, at fair value 128.2 1,029.3 — 1,157.5 Short-term investments trading, at fair value 1.1 0.9 — 2.0 Privately-held investments — — 307.1 307.1 Catastrophe bonds trading, at fair value — 3.4 — 3.4 Other investments (1) — — — 151.3 Other financial assets and liabilities, at fair value Derivatives at fair value — foreign exchange contracts — 12.9 — 12.9 Liabilities under derivative contracts — foreign exchange contracts — (13.3) — (13.3) Total $ 1,384.5 $ 4,669.7 $ 307.1 $ 6,512.6 ________________ (1) Other investments represents our investments in real estate funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 20(a), “Commitments and Contingencies.” The following tables present the level within the fair value hierarchy at which the Company’s financial assets and liabilities are measured on a recurring basis as at June 30, 2023 and December 31, 2022: As at June 30, 2023 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 1,013.8 $ — $ — $ 1,013.8 U.S. agency — 8.2 — 8.2 Municipal — 149.5 — 149.5 Corporate — 1,875.9 — 1,875.9 Non-U.S. government-backed corporate — 110.9 — 110.9 Non-U.S. government 192.7 76.5 — 269.2 Non-agency commercial mortgage-backed — 5.7 — 5.7 Agency mortgage-backed — 475.0 — 475.0 Total fixed income securities available for sale, at fair value 1,206.5 2,701.7 — 3,908.2 Short-term investments available for sale, at fair value 169.2 0.1 — 169.3 Fixed income securities, trading, at fair value 235.0 — — 235.0 Municipal — 3.1 — 3.1 Corporate — 165.4 — 165.4 Non-U.S. government-backed corporate — 9.6 — 9.6 High yield loans — 86.6 — 86.6 Non-U.S. government 12.7 21.4 — 34.1 Asset-backed — 924.6 — 924.6 Agency mortgage-backed — 20.1 — 20.1 Total fixed income securities trading, at fair value 247.7 1,230.8 — 1,478.5 Short-term investments trading, at fair value 9.1 1.9 — 11.0 Privately-held investments trading, at fair value — — 482.4 482.4 Catastrophe bonds trading, at fair value — 2.4 — 2.4 Other investments (1) — — — 213.4 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 17.2 — 17.2 Derivative liabilities — foreign exchange contracts — (13.4) — (13.4) Derivative liabilities — loss portfolio transfer (2) — — (23.4) (23.4) Total 1,632.5 3,940.7 459.0 6,245.6 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate and other funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.” (2) The loss portfolio transfer contract includes a funds withheld arrangement that provides variable interest expense based on Aspen’s investment performance. As a result, this funds withheld arrangement is considered an embedded derivative and accounted for as an option-based derivative. As at December 31, 2022 Level 1 Level 2 Level 3 Total ($ in millions) Fixed income securities, available for sale. at fair value U.S. government $ 953.0 $ — $ — $ 953.0 U.S. agency — 8.8 — 8.8 Municipal — 149.5 — 149.5 Corporate — 1,845.0 — 1,845.0 Non-U.S. government-backed corporate — 110.4 — 110.4 Non-U.S. government 145.3 68.3 — 213.6 Non-agency commercial mortgage-backed — 5.6 — 5.6 Agency mortgage-backed — 502.7 — 502.7 Total fixed income securities available for sale, at fair value 1,098.3 2,690.3 — 3,788.6 Short-term investments available for sale, at fair value 51.9 0.1 — 52.0 Fixed income securities, trading, at fair value U.S. government 261.6 — — 261.6 Municipal — 3.6 — 3.6 Corporate — 162.1 — 162.1 Non-U.S. government-backed corporate — 11.6 — 11.6 High yield loans — 88.3 — 88.3 Non-U.S. government 10.6 19.8 — 30.4 Asset-backed — 896.5 — 896.5 Agency mortgage-backed — 21.4 — 21.4 Total fixed income securities trading, at fair value 272.2 1,203.3 — 1,475.5 Short-term investments trading, at fair value 6.3 — — 6.3 Privately-held investments — — 533.0 533.0 Catastrophe bonds trading, at fair value — 2.9 — 2.9 Other investments (1) — — — 221.3 Other financial assets and liabilities, at fair value Derivative assets — foreign exchange contracts — 56.2 — 56.2 Derivative liabilities — foreign exchange contracts — (3.2) — (3.2) Derivative liabilities — loss portfolio transfer — — (31.7) (31.7) Total $ 1,428.7 $ 3,949.6 $ 501.3 $ 6,100.9 ________________ (1) Other investments represents our investments in real estate, infrastructure and direct lending funds and are measured at fair value using the net asset value per share practical expedient. As a result this has not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. The investment in the real estate funds is subject to restrictions as detailed in Note 12(a), “Commitments and Contingencies.”
Fair Value, Measured on a Recurring Basis, Gain (Loss) Included in Earnings	The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Lev el 3 inputs for the twelve months ended December 31, 2022 and December 31, 2021: Twelve Months Ended December 31, 2022 Balance at beginning of year Purchases and issuances Transfers in/(out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of year Change in unrealized investment gains (losses) relating to assets held at end of year Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Liabilities under derivative contracts - loss $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Twelve Months Ended December 31, 2021 Assets Privately-held investments — trading Commercial mortgage loans $ 163.6 $ 169.9 $ — $ (122.5) $ 0.5 $ 211.5 $ (0.5) Middle market loans 112.1 5.6 — (56.1) 3.7 65.3 (1.5) Asset-backed securities 18.6 10.0 — (1.8) (0.1) 26.7 (0.2) Equity securities 5.0 0.1 — (1.6) 0.1 3.6 — Preference shares — 19.5 (19.5) — — — — Total Level 3 assets $ 299.3 $ 205.1 $ (19.5) $ (182.0) $ 4.2 $ 307.1 $ (2.2) Valuation of Fixed Income Securities . The following table presents a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Level 3 inputs for the six months ended June 30, 2023 and the twelve months ended December 31, 2022: Six Months Ended June 30, 2023 Balance at beginning of period Purchases and issuances Transfers (out) Settlements and sales Increase/(decrease) in fair value including net income Balance at end of period Change in unrealized investment gains (losses) relating to assets held at end of period Assets Privately-held investments — trading Commercial mortgage loans $ 312.1 $ 15.9 $ — $ (23.2) $ (9.8) $ 295.0 $ (10.5) Middle market loans 106.9 0.1 — (5.4) 0.5 102.1 (2.0) Asset-backed securities 66.8 — (5.5) (3.8) 0.9 58.4 (1.1) Global corporate securities 15.0 — — (0.2) — 14.8 (0.1) Equity securities 6.6 7.0 (1.2) (0.2) (0.1) 12.1 — Short-term investments 25.6 — — (25.6) — — — Total Level 3 assets $ 533.0 $ 23.0 $ (6.7) $ (58.4) $ (8.5) $ 482.4 $ (13.7) Liabilities Derivative liabilities - loss portfolio transfer $ (31.7) $ — $ — $ — $ 8.3 $ (23.4) $ — Total Level 3 liabilities $ (31.7) $ — $ — $ — $ 8.3 $ (23.4) $ — Twelve Months Ended December 31, 2022 Assets Privately-held investments — trading Commercial mortgage loans $ 211.5 $ 215.7 $ — $ (113.1) $ (2.0) $ 312.1 $ (0.5) Middle market loans 65.3 61.8 — (19.3) (0.9) 106.9 (2.1) Asset-backed securities 26.7 54.5 — (12.6) (1.8) 66.8 (2.0) Global corporate securities — 15.1 — — (0.1) 15.0 — Equity securities 3.6 5.5 — (2.4) (0.1) 6.6 — Short-term investments — 25.6 — — — 25.6 — Total Level 3 assets $ 307.1 $ 378.2 $ — $ (147.4) $ (4.9) $ 533.0 $ (4.6) Liabilities Derivative liabilities - loss portfolio transfer $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ — Total Level 3 liabilities $ — $ (17.2) $ — $ — $ (14.5) $ (31.7) $ —
Fair Value Inputs, and Valuation Techniques	The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at December 31, 2022: At December 31, 2022 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 200.7 Discounted cash flow Discount rate 3.9 % 9.4 % 5.3 % Commercial mortgage loans 85.8 Transaction Value n/a n/a n/a n/a Commercial mortgage loans 25.6 Liquidation method n/a n/a n/a n/a Middle market loans 106.9 Discounted cash flow Discount rate 7.4 % – 18.5 % 9.9 % Asset-backed securities 66.8 Discounted cash flow Discount rate 5.8 % – 9.3 % 6.7 % Global corporate securities 15.0 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Equity securities 5.3 Discounted cash flow Discount rate 9.0 % – 12.5 % 9.1 % Equity securities 1.3 Transaction Value n/a n/a n/a n/a Short-term investments 25.6 Discounted cash flow Discount rate 6.4 % – 6.4 % 6.4 % Total $ 533.0 The following table summarizes the quantitative inputs and assumptions used for financial assets and liabilities investments categorized as Level 3 under the fair value hierarchy as at June 30, 2023: At June 30, 2023 Fair Value Valuation Techniques Unobservable (U) inputs Ranges Weighted Average ($ in millions) Privately-held investments — Trading Commercial mortgage loans $ 270.0 Discounted cash flow Discount rate 3.7% - 11.2% 6.2% Commercial mortgage loans 25.0 3rd party NAV n/a n/a n/a n/a Middle market loans 102.1 Discounted cash flow Discount rate 7.6% - 20.9% 10.8% Asset-backed securities 58.4 Discounted cash flow Discount rate 5.8% - 9.3% 6.8% Global corporate securities 14.8 Discounted cash flow Discount rate 6.4% - 7.4% 6.4% Equity securities 12.1 Discounted cash flow Discount rate 8.6% - 8.6% 8.6% Total $ 482.4

Reinsurance (Tables)_2

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2023
Reinsurance Disclosures [Abstract]
Summary of Assumed and Ceded Reinsurance on Premiums Written, Premiums Earned and Insurance Losses and Loss Adjustment Expenses	The effect of assumed and ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the twelve months ended December 31, 2022, 2021 and 2020 was as follows: Twelve Months Ended December 31, 2022 2021 2020 ($ in millions) Premiums written: Direct $ 2,531.7 $ 2,341.4 $ 2,042.1 Assumed 1,807.0 1,597.0 1,656.4 Ceded (1,442.7) (1,350.7) (1,120.7) Net premiums written $ 2,896.0 $ 2,587.7 $ 2,577.8 Premiums earned: Direct $ 2,370.8 $ 2,139.1 $ 2,026.4 Assumed 1,617.2 1,479.2 1,612.0 Ceded (1,299.3) (1,207.8) (1,110.9) Net premiums earned $ 2,688.7 $ 2,410.5 $ 2,527.5 Insurance losses and loss adjustment expenses: Direct $ 1,574.2 $ 1,499.8 $ 1,479.6 Assumed 939.5 1,000.6 1,134.5 Ceded (833.7) (807.1) (773.3) Net insurance losses and loss adjustment expenses $ 1,680.0 $ 1,693.3 $ 1,840.8 The effect of ceded reinsurance on premiums written, premiums earned and insurance losses and loss adjustment expenses for the six months ended June 30, 2023 and 2022 was as follows: Six Months Ended June 30, 2023 2022 ($ in millions) Premiums written: Insurance $ 1,249.5 $ 1,305.7 Reinsurance 875.7 1,045.6 Ceded (774.7) (845.2) Net premiums written $ 1,350.5 $ 1,506.1 Premiums earned: Insurance $ 1,203.6 $ 1,171.5 Reinsurance 755.7 776.9 Ceded (671.9) (621.2) Net premiums earned $ 1,287.4 $ 1,327.2 Insurance losses and loss adjustment expenses: Insurance $ 691.7 $ 719.2 Reinsurance 353.4 402.4 Ceded (328.0) (353.9) Net insurance losses and loss adjustment expenses $ 717.1 $ 767.7

Derivative Contracts (Tables)_2

Derivative Contracts (Tables)	6 Months Ended
	Jun. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at December 31, 2022 and 2021: As at December 31, 2022 As at December 31, 2021 Derivatives Not Designated as Hedging Instruments Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivatives at Fair Value $ 945.8 $ 41.9 $ 759.8 $ 12.9 Foreign Exchange Contracts Liabilities under Derivative Contracts $ 729.5 $ (3.2) $ 785.9 $ (12.4) Loss Portfolio Transfer Liability - Embedded Derivative (2) Liabilities under Derivative Contracts — $ (31.7) — — ________________ (1) Fair value is net of $3.7 million of cash collateral (December 31, 2021 — $2.1 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. Refer to Note 7 for further information. As at December 31, 2022 As at December 31, 2021 Derivatives Designated as Hedging Instruments Under ASC 815 Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivatives at Fair Value $ 109.7 $ 14.3 $ — $ — Foreign Exchange Contracts Liabilities under Derivative Contracts $ — $ — $ 143.1 $ (0.9) The following table summarizes information on the location and amounts of derivative fair values on the consolidated balance sheet as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Derivatives Not Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts (1) Derivative assets $ 670.6 $ 7.2 $ 945.8 $ 41.9 Foreign Exchange Contracts Derivative liabilities $ 1,213.4 $ (13.4) $ 729.5 $ (3.2) Loss Portfolio Transfer Liability - Embedded Derivative (2) Derivative liabilities — $ (23.4) — (31.7) ________________ (1) Fair value is net of $2.7 million of cash collateral (December 31, 2022 — $3.7 million). (2) The LPT contains an embedded derivative within the contract in relation to the variable interest crediting rate. As at June 30, 2023 As at December 31, 2022 Derivatives Designated as Hedging Balance Sheet Location Notional Fair Notional Fair ($ in millions) ($ in millions) Foreign Exchange Contracts Derivative assets $ 54.7 $ 10.0 $ 109.7 $ 14.3
Gain/(Loss) Recognized in Income on Derivative	The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging” for the twelve months ended December 31, 2022 and 2021: Amount of (Loss)/Gain Recognized on Derivatives For the Twelve Months Ended Location of Gain/(Loss) December 31, 2022 December 31, 2021 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives (80.5) (35.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations 5.9 (5.7) Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income 15.4 (6.2) The following table provides the unrealized and realized gains/(losses) recorded in the consolidated statements of operations and other comprehensive income for derivatives that are not designated or designated as hedging instruments under ASC 815 — “ Derivatives and Hedging ” for the six months ended June 30, 2023 and 2022: For the Six Months Ended Location of Gain/(Loss) June 30, 2023 June 30, 2022 Derivatives not designated as hedges ($ in millions) Foreign Exchange Contracts Change in Fair Value of Derivatives 19.6 (84.9) Derivatives designated as hedges Foreign Exchange Contracts General, administrative and corporate expenses in consolidated statement of operations (3.7) 2.8 Foreign Exchange Contracts Net change from current period hedged transactions in other comprehensive income (4.3) (6.4)

Reserves for Losses and Adjus_4

Reserves for Losses and Adjustment Expenses (Tables)	6 Months Ended
	Jun. 30, 2023
Insurance [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the twelve months ended December 31, 2022, 2021 and 2020: As at December 31, 2022 2021 2020 ($ in millions) Provision for losses and LAE at the start of the year $ 7,611.8 $ 7,165.3 $ 6,951.8 Less reinsurance recoverable (3,298.1) (3,195.2) (2,319.8) Net loss and LAE at the start of the year 4,313.7 3,970.1 4,632.0 Net loss and LAE expenses disposed (1) (1,840.1) — (818.5) Movement in net provision for losses and LAE for claims incurred: Current year 1,651.9 1,648.2 1,841.7 Prior years 28.1 45.1 (0.9) Total incurred 1,680.0 1,693.3 1,840.8 Net Losses and LAE payments for claims incurred: Current year (192.7) (729.1) (404.9) Prior years (1,098.4) (580.7) (1,359.7) Total paid (1,291.1) (1,309.8) (1,764.6) Foreign exchange (gains)/losses (49.3) (39.9) 80.4 Net losses and LAE reserves at the end of the year 2,813.2 4,313.7 3,970.1 Plus reinsurance recoverable on unpaid losses at the end of the year 4,897.7 3,298.1 3,195.2 Provision for losses and LAE at the end of the year $ 7,710.9 $ 7,611.8 $ 7,165.3 ________________ (1) The following table represents a reconciliation of beginning and ending consolidated loss and LAE reserves for the six months at June 30, 2023 and June 30, 2022: As at June 30, As at June 30, 2023 2022 ($ in millions) Provision for losses and LAE at the start of the period $ 7,710.9 $ 7,611.8 Less reinsurance recoverable (4,897.7) (3,298.1) Net loss and LAE at the start of the period 2,813.2 4,313.7 Net loss and LAE expenses transferred (1) — (1,840.1) Movement in net provision for losses and LAE for claims incurred: Current year 723.5 775.0 Prior years (6.4) (7.3) Total incurred 717.1 767.7 Net Losses and LAE payments for claims incurred: Current year (30.8) (35.5) Prior years (438.6) (616.9) Total paid (469.4) (652.4) Foreign exchange losses/(gains) 22.0 (83.6) Net losses and LAE reserves at the end of the period 3,082.9 2,505.3 Plus reinsurance recoverable on unpaid losses at the end of the period 4,658.0 5,006.5 Provision for losses and LAE at the end of the period $ 7,740.9 $ 7,511.8 __________________ (1)

Capital Structure (Tables)_2

Capital Structure (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Summary of Authorized and Issued Share Capital	The following table provides a summary of the Company’s authorized and issued share capital as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2021 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2021 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 ________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares. The following table provides a summary of the Company’s authorized and issued share capital as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 Number $ in Number $ in Authorized share capital: Ordinary Shares $0.01 per share (2022 — $0.01 per share) 70,000,000 700 70,000,000 700 Preference Shares 0.15144558¢ per share 30,000,000 45 30,000,000 45 Total authorized share capital 745 745 Issued share capital: Issued ordinary shares $0.01 per share (2022 — $0.01 per share) 60,395,839 604 60,395,839 604 Issued 5.950% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 11,000,000 17 11,000,000 17 Issued 5.625% preference shares of 0.15144558¢ each with a liquidation preference of $25 per share 10,000,000 15 10,000,000 15 Issued 5.625% preference shares of 0.15144558¢ represented by depositary shares, each with a liquidation preference of $25 per share (1) 10,000 — 10,000 — Total issued share capital 636 636 __________________ (1) Each depositary share represents a 1/1000 th interest in a share of the 5.625% preference shares.

Dividends (Tables)_2

Dividends (Tables)	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Summary of Declared Dividends	Dividends. On March 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 April 1, 2023 March 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 April 1, 2023 March 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 April 1, 2023 March 15, 2023 ________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share. Dividends . On June 1, 2023, the Company’s Board of Directors declared the following dividends: Dividend Payable on: Record Date: 5.950% Preference Shares (AHL PRC) $ 0.3719 July 1, 2023 June 15, 2023 5.625% Preference Shares (AHL PRD) $ 0.3516 July 1, 2023 June 15, 2023 5.625% Preference Shares, represented by depositary shares (AHL PRE) (1) $ 351.56 July 1, 2023 June 15, 2023 __________________ (1) The 5.625% Preference Shares are represented by depositary shares, each representing a 1/1000 th interest in a share of the 5.625% Preference Shares. The dividend paid per depositary share is likewise 1/1000 th of the declared dividend, equivalent to $0.35156 per depositary share.

Commitments and Contingencies_3

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Company's Restricted Assets	The following table details the forms and value of Company’s material restricted assets as at December 31, 2022 and 2021: As at December 31, 2022 At December 31, 2021 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 707.1 $ 891.3 Third party 2,817.7 3,099.7 Letters of credit / guarantees (1) 471.3 539.8 Total restricted assets (excluding illiquid assets) 3,996.1 4,530.8 Other investments — illiquid assets 221.3 151.3 Total restricted assets and illiquid assets $ 4,217.4 $ 4,682.1 Total as percent of cash and invested assets (2) 59.4 % 59.7 % ________________ (1) As at December 31, 2022, the Company had pledged funds of $471.3 million (December 31, 2021 — $539.8 million) as collateral for the secured letters of credit. (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased. The following table details the forms and value of Company’s material restricted assets as at June 30, 2023 and December 31, 2022: As at June 30, 2023 As at December 31, 2022 ($ in millions, except percentages) Regulatory trusts and deposits: Affiliated transactions $ 617.0 $ 707.1 Third party 2,773.8 2,817.7 Letters of credit / guarantees (1) 266.5 471.3 Total restricted assets (excluding illiquid assets) 3,657.3 3,996.1 Other investments — illiquid assets 213.4 221.3 Total restricted assets and illiquid assets $ 3,870.7 $ 4,217.4 Total as percent of cash and investable assets (2) 52.6 % 59.4 % __________________ (1) As at June 30, 2023, the Company had pledged funds as collateral for the secured letters of credit of $266.5 million (December 31, 2022 — $471.3 million). (2) Investable assets comprise total investments, cash and cash equivalents, accrued interest, receivables for securities sold and payables for securities purchased.

Reclassifications from Accumu_4

Reclassifications from Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income Reclassification	The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the twelve months ended December 31, 2022 and 2021: Amount Reclassified from AOCI Details about the AOCI Components Twelve Months Ended December 31, 2022 Twelve Months Ended December 31, 2021 Affected Line Item in the ($ in millions) Available for sale: Realized (gains) on sale of securities and cash and cash equivalents $ (3.9) $ (24.8) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 58.9 4.4 Realized and unrealized investment losses 55.0 (20.4) Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 55.0 $ (20.4) Net income/(loss) Realized derivatives: Net realized gains on settled derivatives 15.4 (6.2) General, administrative and corporate expenses Tax on settled derivatives — — Income tax (expense)/benefit $ 15.4 $ (6.2) Net income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 70.4 $ (26.6) Net income/(loss) The following table sets out the components of the Company’s AOCI that are reclassified into the condensed consolidated statement of operations for the six months ended June 30, 2023 and 2022: Amount Reclassified from AOCI Details about the AOCI Components Six Months Ended June 30, 2023 Six Months Ended June 30, 2022 Affected Line Item in the ($ in millions) Available for sale: Realized gains on sale of securities and cash and cash equivalents $ (0.4) $ (2.3) Realized and unrealized investment gains Realized losses on sale of securities and cash and cash equivalents 7.2 30.1 Realized and unrealized investment losses 6.8 27.8 Income/(loss) from operations before income tax Tax on net realized gains of securities — — Income tax (expense)/benefit $ 6.8 $ 27.8 Net income/(loss) Realized derivatives: Net realized loss on settled derivatives (4.3) (6.4) General, administrative and corporate expenses Tax on settled derivatives — 0.6 Income tax (expense)/benefit $ (4.3) $ (5.8) Net Income/(loss) Total reclassifications from AOCI to the statement of operations, net of income tax $ 2.5 $ 22.0 Net income/(loss)

Basis of Preparation and Sign_5

Basis of Preparation and Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 period
Property, Plant and Equipment [Line Items]
Non-Payment Of Dividends, Number Of Periods	6
Computer Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Computer Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	4 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years

Segment Reporting - Additional

Segment Reporting - Additional Information - Narrative (Details) - segement	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Segment Reporting [Abstract]
Number of business segments	2	2

Segment Reporting - Summary of

Segment Reporting - Summary of Gross and Net Written and Earned Premiums, Underwriting Results, Ratios and Reserves for Each of Company's Business Segments (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Net written premiums	1,350.5	1,506.1	2,896	2,587.7	2,577.8
Gross earned premiums			3,988	3,618.3	3,638.4
Net earned premiums	1,287.4	1,327.2	2,688.7	2,410.5	2,527.5
Losses and loss adjustment expenses	717.1	767.7	1,680	1,693.3	1,840.8
Acquisition costs	192.9	216.5	431.8	414.1	465.7
General and administrative expenses	169	186.5	386.5	333.1	308
Underwriting income (loss)	208.4	156.5	190.4	(30)	(87)
Corporate Expenses	(53.1)	(37.5)	(71.7)	(64.3)	(70.2)
Non-operating expenses (1)	(10.6)	(3.6)	(36)	(20.6)	(32.7)
Net investment income (1)	129.4	88.7	188.1	147.5	154.6
Realized and unrealized investment gains	36.1	2.5	5	56.2	98.5
Realized and unrealized investment losses	(18.1)	(128.9)	(182.6)	(47.4)	(27.4)
Change in fair value of derivatives	19.6	(84.9)	(80.5)	(35.9)	(65.1)
Interest Expense, Debt	(42.9)	(9.1)	(43.7)	(14.3)	(33.9)
Net realized and unrealized foreign exchange gains	(13.7)	75.2	15.9	40	(13.8)
Other income			8.2	14.7	49.8
Other expenses			20.1	10.8	10.8
Income (loss) from operations before income taxes	255.1	53.1	(27)	35.1	(38)
Income Tax Expense (Benefit)	(36.2)	(4.7)	78.1	(5.3)	(18.4)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Losses and loss adjustment expenses	7,740.9	7,511.8	7,710.9	7,611.8	7,165.3	$ 6,951.8
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total	$ 3,082.9	$ 2,505.3	$ 2,813.2	$ 4,313.7	$ 3,970.1	$ 4,632
Ratios
Loss ratio	55.70%	57.80%	62.50%	70.20%	72.80%
Acquisition cost ratio	15%	16.30%	16.10%	17.20%	18.40%
General and administrative expense ratio	13.10%	14.10%	14.40%	13.80%	12.20%
Expense ratio	28.10%	30.40%	30.50%	31%	30.60%
Combined ratio	83.80%	88.20%	93%	101.20%	103.40%
Non-operating expenses related to fixed income writeoff			$ 32.7
Non-operating expenses related to severance, retention awards and other non-recurring costs			10		$ 18.2
Non-operating expenses related to impairment charges on lease assets			6.7	$ 0.4	12.9
Non-operating expenses related to Merger Agreement				19.3
Non-operating expenses related to Effectiveness And Efficiency Program				0.9	1.6
Reinsurance
Segment Reporting Information [Line Items]
Net written premiums			1,426.4	1,199	1,297.7
Net earned premiums			1,251.8	1,118.8	1,287.7
Losses and loss adjustment expenses	$ 1,441.2	$ 1,190.4	1,360.7	2,148.4	2,095.7
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total			$ 1,360.7	$ 2,148.4	$ 2,095.7
Ratios
Loss ratio	52%	61.40%	61.50%	63%	74.40%
Acquisition cost ratio	18.50%	20.70%	20.20%	19.80%	19.10%
General and administrative expense ratio	10.20%	11.60%	11.40%	10.80%	8.60%
Expense ratio	28.70%	32.30%	31.60%	30.60%	27.70%
Combined ratio	80.70%	93.70%	93.10%	93.60%	102.10%
Insurance
Segment Reporting Information [Line Items]
Net written premiums			$ 1,469.6	$ 1,388.7	$ 1,280.1
Net earned premiums			1,436.9	1,291.7	1,239.8
Losses and loss adjustment expenses	$ 1,641.7	$ 1,314.9	1,452.5	2,165.3	1,874.4
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total			$ 1,452.5	$ 2,165.3	$ 1,874.4
Ratios
Loss ratio	58.70%	54.90%	63.30%	76.50%	71.10%
Acquisition cost ratio	12.20%	12.70%	12.50%	14.90%	17.70%
General and administrative expense ratio	15.50%	16.10%	17%	16.40%	15.90%
Expense ratio	27.70%	28.80%	29.50%	31.30%	33.60%
Combined ratio	86.40%	83.70%	92.80%	107.80%	104.70%
Operating Segments | Reinsurance
Segment Reporting Information [Line Items]
Gross written premiums	$ 875.7	$ 1,045.6	$ 1,807	$ 1,597	$ 1,656.4
Net written premiums	605	783.7	1,426.4	1,199	1,297.7
Gross earned premiums			1,617.2	1,479.2	1,612
Net earned premiums	572	600.8	1,251.8	1,118.8	1,287.7
Losses and loss adjustment expenses	297.2	369	770.3	705.2	958.6
Acquisition costs	105.7	124.1	252.4	221.6	246
General and administrative expenses	58.4	69.7	142.5	121.3	110.8
Underwriting income (loss)	110.7	38	86.6	70.7	(27.7)
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Gross written premiums	1,249.5	1,305.7	2,531.7	2,341.4	2,042.1
Net written premiums	745.5	722.4	1,469.6	1,388.7	1,280.1
Gross earned premiums			2,370.8	2,139.1	2,026.4
Net earned premiums	715.4	726.4	1,436.9	1,291.7	1,239.8
Losses and loss adjustment expenses	419.9	398.7	909.7	988.1	882.2
Acquisition costs	87.2	92.4	179.4	192.5	219.7
General and administrative expenses	110.6	116.8	244	211.8	197.2
Underwriting income (loss)	$ 97.7	$ 118.5	$ 103.8	$ (100.7)	$ (59.3)

Segment Reporting - Summary o_2

Segment Reporting - Summary of the Schedule of the Company's gross written premiums based on the location of the insured risk (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Australia/Asia
Segment Reporting Information [Line Items]
Gross written premiums			257.5	275.8	259.7
Europe
Segment Reporting Information [Line Items]
Gross written premiums			194.5	140.6	92.5
United Kingdom
Segment Reporting Information [Line Items]
Gross written premiums			485.8	393.2	369
United States & Canada
Segment Reporting Information [Line Items]
Gross written premiums			2,715.7	2,301.8	2,267.5
Worldwide excluding United States
Segment Reporting Information [Line Items]
Gross written premiums			24.2	31.5	23.1
Worldwide including United States
Segment Reporting Information [Line Items]
Gross written premiums			541.7	592.2	501.2
Other (4)
Segment Reporting Information [Line Items]
Gross written premiums			$ 119.3	$ 203.3	$ 185.5

Investments - Summary of Invest

Investments - Summary of Investment Income (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ (134.7)	$ (93.5)	$ (198.4)	$ (159.2)	$ (167.3)
Investment expenses	(5.3)	(4.8)	(10.3)	(11.7)	(12.7)
Net investment income	129.4	88.7	188.1	147.5	154.6
Fixed income securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(55.7)	(44.5)	(95.6)	(87.2)	(106.5)
Short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(1.6)	0	(0.6)	(0.1)	(0.8)
Short-term investment, Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(0.1)	0	(0.1)	0	(0.5)
Fixed term deposits (included in cash and cash equivalents)
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(17.3)	(0.5)	(6.6)	(0.7)	(6.4)
Catastrophe bonds — Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(1.1)	(0.1)	(0.3)	(0.9)	(1.4)
Privately-held investments — Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(21.5)	(8.8)	(24.3)	(18.2)	(20.9)
Other investments, at fair value
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	10.4	(20.7)	(13.9)	(21.9)	(2)
Fixed Income Securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ (47.8)	$ (18.9)	$ (57)	$ (30.2)	$ (32.8)

Investments - Net Realized and

Investments - Net Realized and Unrealized Investment Gains and Losses and Change in Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities - gross realized gains	$ 0.4	$ 1.4	$ 2.9	$ 22.7	$ 68.8
Fixed income securities - gross realizes (losses)	(6.9)	(29.9)	(58.4)	(3.6)	(1.8)
Net change in expected credit gains (losses)	3.7	(7.7)	(5)	(2.5)	0.4
Fixed income securities, trading - gross realized gains	0.3	0	0.2	12.2	18.2
Fixed income securities, trading, gross realizes (losses)	(1.1)	(0.2)	(1.8)	(2)	(3.8)
Privately-held investments net unrealized gains/(losses)	31	(89.6)	(113.9)	(23.4)	0
Catastrophe bonds	(0.6)	(0.1)	0.2	(0.8)	0
Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations	18	(126.4)	(177.6)	8.8	71.1
Change in available for sale net unrealized (losses)/gains:
Fixed income securities	12.3	(316)	(391.7)	(157.6)	108.5
Income tax benefit/(expense)	(1.6)	29.5	23.9	(0.3)	(0.5)
Total change in net unrealized (losses)/gains, net of taxes recorded in other comprehensive income	10.7	(286.5)	(367.8)	(157.9)	108
Cash and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities - gross realized gains	0.1	0.9	1	2	0.5
Fixed income securities - gross realizes (losses)	(0.1)	(0.2)	(0.5)	(0.8)	(0.4)
Fixed income securities, trading - gross realized gains	0.1	0	0	0.1	0.2
Fixed income securities, trading, gross realizes (losses)	(0.2)	0	0	(0.3)	(0.3)
Privately-held investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities, trading - gross realized gains	0.1	0.2	0.7	0.6	0
Fixed income securities, trading, gross realizes (losses)			(0.1)	(13.8)	0
Privately-held investments net unrealized gains/(losses)	9	1.3	2.5	(18.1)	20.4
MVI
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment			0	0.1	(0.4)
Multi-Line Insurer
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment	$ 0.4	$ 0.1	(0.4)	0.2	0
Digital Re
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment			0	0	(0.3)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Bene
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross realized gain on sale of equity method investment			0	0	1.8
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Crop Re
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross realized gain on sale of equity method investment			$ 0	$ 0	$ 8.6

Investments - Cost, Gross Unrea

Investments - Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available for Sale Investments in Fixed Income Maturities and Short-Term Investments (Details) $ in Millions	Jun. 30, 2023 USD ($) security Security	Dec. 31, 2022 USD ($)	Dec. 31, 2022 security	Dec. 31, 2022 Security	Dec. 31, 2021 USD ($) security Security
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	$ 3,908.2	$ 3,788.6			$ 4,881.6
Gross unrealized gains	2.4	3.6			95.3
Gross unrealized losses	(321.4)	(338.6)			(34.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(4)	(7.7)			(2.7)
Fixed income securities, available for sale amortized cost	4,231.2	4,131.3			4,823.5
0-12 months, Fair Market Value	1,175.6	2,321.4			2,014.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	32.5	145.4			30.9
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,758.3	3,645.1			2,086.6
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 321.4	339			$ 34.5
Number of Securities | security	1,193		1,166		644
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 288.9	193.6			$ 3.6
Total short-term investments — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross unrealized gains	0	0			0
Gross unrealized losses	0	(0.4)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Total fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	4,077.5	3,840.6			4,891.7
Gross unrealized gains	2.4	3.6			95.3
Gross unrealized losses	(321.4)	(339)			(34.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(4)	(7.7)			(2.7)
Fixed income securities, available for sale amortized cost	4,400.5	4,183.7			4,833.6
Fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
0-12 months, Fair Market Value	1,163.8	2,269.5			2,010.2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	32.5	145			30.9
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,746.5	3,593.2			2,082.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 321.4	338.6			$ 34.5
Number of Securities | Security	1,188			1,165	637
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 288.9	193.6			$ 3.6
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
0-12 months, Fair Market Value	11.8	51.9			4.4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0.4			0
Over 12 months, Fair Market Value	0	0			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	11.8	51.9			4.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0	0.4			$ 0
Number of Securities	5		1	1	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	0			$ 0
U.S. government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,013.8	953			1,084.3
Gross unrealized gains	0	0			24
Gross unrealized losses	(51.1)	(50.7)			(5.9)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	1,064.9	1,003.7			1,066.2
0-12 months, Fair Market Value	494.8	741.1			309.1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	12.8	30.6			4
Over 12 months, Fair Market Value	519.1	203.4			29.3
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,013.9	944.5			338.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 51.1	50.7			$ 5.9
Number of Securities | security	105		118		51
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 38.3	20.1			$ 1.9
U.S. agency
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	8.2	8.8			21.5
Gross unrealized gains	0	0			0.8
Gross unrealized losses	(0.4)	(0.4)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	8.6	9.2			20.7
0-12 months, Fair Market Value	7	7.1			6.1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0.4	0.4			0
Over 12 months, Fair Market Value	1.1	1.7			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	8.1	8.8			6.1
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0.4	0.4			$ 0
Number of Securities | security	4		5		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	0			$ 0
Municipal
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	149.5	149.5			82.6
Gross unrealized gains	0	0			2
Gross unrealized losses	(8.8)	(9.4)			(0.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(0.7)	(1)			(0.1)
Fixed income securities, available for sale amortized cost	159	159.9			81.2
0-12 months, Fair Market Value	90.9	133.1			29.7
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	3.7	7.1			0.5
Over 12 months, Fair Market Value	58.7	16.4			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	149.6	149.5			29.7
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8.8	9.4			$ 0.5
Number of Securities | security	60		59		20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 5.1	2.3			$ 0
Corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,875.9	1,845			2,208.3
Gross unrealized gains	2.4	3.5			47.5
Gross unrealized losses	(155.2)	(169.1)			(13)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(3.2)	(6.3)			(2.3)
Fixed income securities, available for sale amortized cost	2,031.9	2,016.9			2,176.1
0-12 months, Fair Market Value	467.4	1,104.7			804.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	13.1	77.6			11.7
Over 12 months, Fair Market Value	1,254.7	568.2			23.6
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,722.1	1,672.9			828.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 155.2	169.1			$ 13
Number of Securities | security	727		701		400
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 142.1	91.5			$ 1.3
Non-U.S. government-backed corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	110.9	110.4			136.8
Gross unrealized gains	0	0			0.2
Gross unrealized losses	(8.7)	(8.8)			(1.9)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	(0.2)			0
Fixed income securities, available for sale amortized cost	119.6	119.4			138.5
0-12 months, Fair Market Value	5.2	11.3			114.4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0.5			1.9
Over 12 months, Fair Market Value	105.7	99			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	110.9	110.3			114.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8.7	8.8			$ 1.9
Number of Securities | security	16		16		10
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 8.7	8.3			$ 0
Non-U.S government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	269.2	213.6			250.7
Gross unrealized gains	0	0.1			1.4
Gross unrealized losses	(12)	(11.5)			(1.2)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(0.1)	(0.2)			(0.3)
Fixed income securities, available for sale amortized cost	281.3	225.2			250.8
0-12 months, Fair Market Value	80.1	63.8			181.8
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	1.2	2.9			1.2
Over 12 months, Fair Market Value	182.2	135.9			3.1
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	262.3	199.7			184.9
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 12	11.5			$ 1.2
Number of Securities | security	61		45		35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 10.8	8.6			$ 0
Asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value					0.5
Gross unrealized gains					0
Gross unrealized losses					0
Debt Securities, Available-for-Sale, Allowance for Credit Loss					0
Fixed income securities, available for sale amortized cost					0.5
Non-agency commercial mortgage-backed securities
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	5.7	5.6			6.9
Gross unrealized gains	0	0			0.3
Gross unrealized losses	(0.9)	(1)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	6.6	6.6			6.6
0-12 months, Fair Market Value	0	5.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	1
Over 12 months, Fair Market Value	5.6	0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	5.6	5.6
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0.9	1
Number of Securities | security	1		1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0.9	0
Agency mortgage-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	475	502.7			1,090
Gross unrealized gains	0	0			19.1
Gross unrealized losses	(84.3)	(87.7)			(12)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	559.3	590.4			1,082.9
0-12 months, Fair Market Value	18.4	202.8			564.5
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	1.3	24.9			11.6
Over 12 months, Fair Market Value	455.6	299.1			16
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	474	501.9			580.5
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 84.3	87.7			$ 12
Number of Securities | security	214		220		116
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 83	62.8			$ 0.4
Total short-term investments — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	169.3	52			10.1
Fixed income securities, available for sale amortized cost	$ 169.3	$ 52.4			$ 10.1

Investments - Cost, Gross Unr_2

Investments - Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Trading Investments in Fixed Income Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Trading Securities and Other Trading Items [Line Items]
Debt Securities, Trading, Amortized Cost	$ 1,552.7	$ 1,576.7	$ 1,155.5
High yield loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	1.2	0.2	0.1
Gross Unrealized Losses	(0.7)	(2.1)	(0.4)
Fair market value, trading	86.6	88.3	76.9
Debt Securities, Trading, Amortized Cost	86.1	90.2	77.2
Fixed income securities - trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	2.5	0.7	6.2
Gross Unrealized Losses	(76.7)	(101.9)	(4.2)
Fair market value, trading	1,478.5	1,475.5	1,157.5
Debt Securities, Trading, Amortized Cost	1,552.7	1,576.7	1,155.5
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0	0	0
Fair market value, trading	11	6.3	2
Debt Securities, Trading, Amortized Cost	11	6.3	2
Catastrophe Bonds
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0	(2.2)	(1.9)
Fair market value, trading	2.4	2.9	3.4
Debt Securities, Trading, Amortized Cost	2.4	5.1	5.3
Commercial mortgage loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	1.3	0.6	0.4
Gross Unrealized Losses	(11.8)	(1.1)	(0.9)
Fair market value, trading	295	312.1	211.5
Debt Securities, Trading, Amortized Cost	305.5	312.6	212
Middle market loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(2)	(2.1)	(1.5)
Fair market value, trading	102.1	106.9	65.4
Debt Securities, Trading, Amortized Cost	104.1	109	66.9
Securities, asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(1.1)	(2)	(0.2)
Fair market value, trading	58.4	66.8	26.6
Debt Securities, Trading, Amortized Cost	59.5	68.8	26.8
Global corporates securities
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.1)	(0.1)
Fair market value, trading	14.8	15
Debt Securities, Trading, Amortized Cost	14.9	15.1
Equity securities — Trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0.1
Gross Unrealized Losses	0	0	0
Fair market value, trading	12.1	6.6	3.6
Debt Securities, Trading, Amortized Cost	12.1	6.6	3.5
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair market value, trading		25.6
Debt Securities, Trading, Amortized Cost		25.6
Privately-held investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	1.3	0.6	0.5
Gross Unrealized Losses	(15)	(5.3)	(2.6)
Fair market value, trading	482.4	533	307.1
Debt Securities, Trading, Amortized Cost	496.1	537.7	309.2
Total - Trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	3.8	1.3	6.7
Gross Unrealized Losses	(91.7)	(109.4)	(8.7)
Fair market value, trading	1,974.3	2,017.7	1,470
Debt Securities, Trading, Amortized Cost	2,062.2	2,125.8	1,472
U.S. government
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0.6
Gross Unrealized Losses	(6.9)	(6.3)	(0.2)
Fair market value, trading	235	261.6	116.3
Debt Securities, Trading, Amortized Cost	241.9	267.9	115.9
Municipal
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0.1
Gross Unrealized Losses	(0.3)	(0.3)	0
Fair market value, trading	3.1	3.6	4
Debt Securities, Trading, Amortized Cost	3.4	3.9	3.9
Corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0.3	0.3	1.9
Gross Unrealized Losses	(11.8)	(13.5)	(0.8)
Fair market value, trading	165.4	162.1	96.8
Debt Securities, Trading, Amortized Cost	176.9	175.3	95.7
Non-U.S government
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(1.7)	(1.8)	(0.4)
Fair market value, trading	34.1	30.4	34.5
Debt Securities, Trading, Amortized Cost	35.8	32.2	34.9
Asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	1	0.2	3.3
Gross Unrealized Losses	(51.6)	(74)	(1.9)
Fair market value, trading	924.6	896.5	785.7
Debt Securities, Trading, Amortized Cost	975.2	970.3	784.3
Agency mortgage-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0.2
Gross Unrealized Losses	(3.2)	(3.3)	(0.3)
Fair market value, trading	20.1	21.4	30.2
Debt Securities, Trading, Amortized Cost	23.3	24.7	30.3
Non-U.S. government-backed corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	(0.5)	(0.6)	(0.2)
Fair market value, trading	9.6	11.6	13.1
Debt Securities, Trading, Amortized Cost	$ 10.1	$ 12.2	$ 13.3

Investments Investments - Distr

Investments Investments - Distribution of Commercial Mortgage and Middle Market Loans (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Middle market loans
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 102.1	$ 106.9	$ 65.4
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Apartment
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 107.8	$ 115.3	$ 101.6
Concentration risk percentage	36.60%	36.90%	48.10%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Hotel
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 98.1	$ 108	$ 68.8
Concentration risk percentage	33.30%	34.60%	32.50%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Office building
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 45.9	$ 42.1	$ 33.9
Concentration risk percentage	15.50%	13.50%	16%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Other commercial
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 37.9	$ 41.4	$ 7.2
Concentration risk percentage	12.80%	13.30%	3.40%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 3.3	$ 3.3	$ 0
Concentration risk percentage	1.10%	1.10%	0%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Industrial
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 2	$ 2	$ 0
Concentration risk percentage	0.70%	0.60%	0%
Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Materials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 20	$ 19.8	$ 20.9
Concentration risk percentage	19.60%	18.50%	32%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Financials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 48.3	$ 53.1	$ 6.1
Concentration risk percentage	47.30%	49.70%	9.30%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Industrials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 18.6	$ 18.7	$ 18.7
Concentration risk percentage	18.20%	17.50%	28.50%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Consumer discretionary
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 4.9	$ 4.9	$ 4.3
Concentration risk percentage	4.80%	4.60%	6.60%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Energy
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 5.6	$ 5.7	$ 5.6
Concentration risk percentage	5.50%	5.30%	8.60%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Consumer staples
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading		$ 0	$ 4.9
Concentration risk percentage		0%	7.50%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Information technology
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 4.7	$ 4.7	$ 4.9
Concentration risk percentage	4.60%	4.40%	7.50%
Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
U.S. | Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 263.6	$ 269.8	$ 183.7
Concentration risk percentage	89.40%	86.40%	86.90%
U.S. | Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 59.4	$ 64.1	$ 56.2
Concentration risk percentage	58.20%	59.90%	85.90%
International | Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 31.4	$ 42.3	$ 27.8
Concentration risk percentage	10.60%	13.60%	13.10%
International | Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 42.7	$ 42.8	$ 9.2
Concentration risk percentage	41.80%	40.10%	14.10%

Investments Investments - Loan-

Investments Investments - Loan-to-Value Ratios (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Commercial mortgage loans | Less than 50 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	47.5	41.1	0
Commercial mortgage loans | 50 to 60 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	227.3	248.3	131.2
Commercial mortgage loans | 61 to 70 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	20.2	22.7	80.3
Middle market loans
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	102.1	106.9	65.4
Middle market loans | Less than 50 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	63.5	63.5	11
Middle market loans | 50 to 60 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	23.3	16.4	9.2
Middle market loans | 61 to 70 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	$ 15.3	27	15.8
Middle market loans | 71 to 80 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading		0	5.6
Middle market loans | 80 to 100 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading		0	12
Middle market loans | Greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading		$ 0	$ 11.8

Investments Investments - Debt

Investments Investments - Debt Service and Fixed Charge Coverage Ratios (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Commercial mortgage loans	295	292.2	147.5
Delinquent amount of loans at end of period	0	19.9	64
Commercial mortgage loans | Nonperforming loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0	0	0
Commercial mortgage loans | Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	47.5	41.1	0
Commercial mortgage loans | 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	227.3	248.3	131.2
Commercial mortgage loans | 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	20.2	22.7	80.3
Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	102.1	106.9	65.4
Middle market loans | Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	63.5	63.5	11
Middle market loans | 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	23.3	16.4	9.2
Middle market loans | 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	15.3	27	15.8
Middle market loans | 71 to 80 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading		0	5.6
Middle market loans | 80 to 100 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading		0	12
Greater than 1.20x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	112.3	106.1	66.3
Greater than 1.20x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	78.9	95.2	25.8
1.00 - 1.20x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	182.7	186.1	62.4
1.00 - 1.20x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	3.8	3.8	22.8
Less than 1.00x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0	0	18.8
Less than 1.00x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 19.4	$ 7.9	$ 16.8

Investments - Other Investments

Investments - Other Investments (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2021	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		$ 6.2	$ 3.9	$ 0.9
Investment in the period		0.4	2	3.2
Proceeds from Sale of Equity Method Investments			0	(0.5)
Closing value of investment, ending balance		7	6.2	3.9
Fair Value, Recurring [Member] | Real estate fund (Dec 2017)
Equity Method Investment, Aggregate Cost [Roll Forward]
Investments, fair value		125.2	134.6	129.9
Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0.4	0.3	0.3
MVI
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		0.8	0.5	0
Investment in the period	$ 0.8	0	0.4	0.4
Proceeds from Sale of Equity Method Investments			0	0
Closing value of investment, ending balance		0.8	0.8	0.5
MVI | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0	(0.1)	0.1
Digital Re
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		0.2	0.2	0.4
Investment in the period		0	0	0.3
Proceeds from Sale of Equity Method Investments			0	(0.5)
Closing value of investment, ending balance		0.2	0.2	0.2
Digital Re | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0	0	0
Multi-Line Insurer
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		5.2	3.2	0.5
Investment in the period		0.4	1.6	2.5
Proceeds from Sale of Equity Method Investments			0	0
Closing value of investment, ending balance		6	5.2	3.2
Multi-Line Insurer | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		$ 0.4	$ 0.4	$ 0.2

Investments - Summary of Fixed

Investments - Summary of Fixed Maturities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 4,231.2	$ 4,131.3	$ 4,823.5
Available for sale investments in fixed income maturities, Fair Market Value	3,908.2	3,788.6	4,881.6
Total fixed income securities — Available for sale
Debt Securities, Available-for-sale [Line Items]
Due one year or less, Cost or Amortized Cost	242.4	179.1	545.1
Due after one year through five years, Cost or Amortized Cost	2,736.2	2,526.9	2,057.2
Due after five years through ten years, Cost or Amortized Cost	684.9	815.1	1,090.5
Due after ten years, Cost or Amortized Cost	1.8	13.2	40.7
Fixed income securities, available for sale amortized cost	3,665.3	3,534.3	3,733.5
Due one year or less, Fair Market Value	$ 236.5	$ 176	$ 549
Available For Sale Securities Debt Maturities Within One Year Average Ratings By Maturity	AA	AA+	AA-
Due after one year through five years, Fair Market Value	$ 2,594.7	$ 2,385.7	$ 2,087.5
Available For Sale Securities Debt Maturities After One Through Five Years Average Ratings By Maturity	AA-	AA-	AA-
Due after five years through ten years, Fair Market Value	$ 595.2	$ 707.7	$ 1,106.3
Available For Sale Securities Debt Maturities After Five Through Ten Years Average Ratings By Maturity	A+	A+	A+
Due after ten years, Fair Market Value	$ 1.1	$ 10.9	$ 41.4
Available For Sale Securities Debt Maturities After Ten Years Average Ratings By Maturity	BB	A-	A-
Available for sale investments in fixed income maturities, Fair Market Value	$ 3,427.5	$ 3,280.3	$ 3,784.2
Agency mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	559.3	590.4	1,082.9
Available for sale investments in fixed income maturities, Fair Market Value	$ 475	$ 502.7	$ 1,090
Available For Sale Securities Average Ratings By Maturity	AA+	AA+	AA+
Non-agency commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 6.6	$ 6.6	$ 6.6
Available for sale investments in fixed income maturities, Fair Market Value	$ 5.7	$ 5.6	$ 6.9
Available For Sale Securities Average Ratings By Maturity	AA+	AA+	AA+
Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 4,231.2	$ 4,131.3	$ 4,823.5
Available for sale investments in fixed income maturities, Fair Market Value	$ 3,908.2	$ 3,788.6	4,881.6
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost			0.5
Available for sale investments in fixed income maturities, Fair Market Value			$ 0.5
Available For Sale Securities Average Ratings By Maturity			AAA

Investments - Aggregate Fair Va

Investments - Aggregate Fair Value and Gross Unrealized Loss by Type of Security (Details) $ in Millions	Jun. 30, 2023 USD ($) security Security	Dec. 31, 2022 USD ($)	Dec. 31, 2022 security	Dec. 31, 2022 Security	Dec. 31, 2021 USD ($) security Security
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 1,175.6	$ 2,321.4			$ 2,014.6
Gross unrealized losses, less than twelve months	(32.5)	(145.4)			(30.9)
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Over 12 months, Gross Unrealized Losses	(288.9)	(193.6)			(3.6)
Total, Fair Market Value	3,758.3	3,645.1			2,086.6
Total, Gross Unrealized Losses	$ (321.4)	(339)			$ (34.5)
Number of Securities | security	1,193		1,166		644
Fixed income securities — Available for sale
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 1,163.8	2,269.5			$ 2,010.2
Gross unrealized losses, less than twelve months	(32.5)	(145)			(30.9)
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Over 12 months, Gross Unrealized Losses	(288.9)	(193.6)			(3.6)
Total, Fair Market Value	3,746.5	3,593.2			2,082.2
Total, Gross Unrealized Losses	$ (321.4)	(338.6)			$ (34.5)
Number of Securities | Security	1,188			1,165	637
Short-term investments
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 11.8	51.9			$ 4.4
Gross unrealized losses, less than twelve months	0	(0.4)			0
Over 12 months, Fair Market Value	0	0			0
Over 12 months, Gross Unrealized Losses	0	0			0
Total, Fair Market Value	11.8	51.9			4.4
Total, Gross Unrealized Losses	$ 0	(0.4)			$ 0
Number of Securities	5		1	1	7
U.S. government
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 494.8	741.1			$ 309.1
Gross unrealized losses, less than twelve months	(12.8)	(30.6)			(4)
Over 12 months, Fair Market Value	519.1	203.4			29.3
Over 12 months, Gross Unrealized Losses	(38.3)	(20.1)			(1.9)
Total, Fair Market Value	1,013.9	944.5			338.4
Total, Gross Unrealized Losses	$ (51.1)	(50.7)			$ (5.9)
Number of Securities | security	105		118		51
U.S. agency
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 7	7.1			$ 6.1
Gross unrealized losses, less than twelve months	(0.4)	(0.4)			0
Over 12 months, Fair Market Value	1.1	1.7			0
Over 12 months, Gross Unrealized Losses	0	0			0
Total, Fair Market Value	8.1	8.8			6.1
Total, Gross Unrealized Losses	$ (0.4)	(0.4)			$ 0
Number of Securities | security	4		5		5
Municipal
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 90.9	133.1			$ 29.7
Gross unrealized losses, less than twelve months	(3.7)	(7.1)			(0.5)
Over 12 months, Fair Market Value	58.7	16.4			0
Over 12 months, Gross Unrealized Losses	(5.1)	(2.3)			0
Total, Fair Market Value	149.6	149.5			29.7
Total, Gross Unrealized Losses	$ (8.8)	(9.4)			$ (0.5)
Number of Securities | security	60		59		20
Corporate
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 467.4	1,104.7			$ 804.6
Gross unrealized losses, less than twelve months	(13.1)	(77.6)			(11.7)
Over 12 months, Fair Market Value	1,254.7	568.2			23.6
Over 12 months, Gross Unrealized Losses	(142.1)	(91.5)			(1.3)
Total, Fair Market Value	1,722.1	1,672.9			828.2
Total, Gross Unrealized Losses	$ (155.2)	(169.1)			$ (13)
Number of Securities | security	727		701		400
Non-U.S. government-backed corporate
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 5.2	11.3			$ 114.4
Gross unrealized losses, less than twelve months	0	(0.5)			(1.9)
Over 12 months, Fair Market Value	105.7	99			0
Over 12 months, Gross Unrealized Losses	(8.7)	(8.3)			0
Total, Fair Market Value	110.9	110.3			114.4
Total, Gross Unrealized Losses	$ (8.7)	(8.8)			$ (1.9)
Number of Securities | security	16		16		10
Non-U.S government
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 80.1	63.8			$ 181.8
Gross unrealized losses, less than twelve months	(1.2)	(2.9)			(1.2)
Over 12 months, Fair Market Value	182.2	135.9			3.1
Over 12 months, Gross Unrealized Losses	(10.8)	(8.6)			0
Total, Fair Market Value	262.3	199.7			184.9
Total, Gross Unrealized Losses	$ (12)	(11.5)			$ (1.2)
Number of Securities | security	61		45		35
Agency mortgage-backed
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 18.4	202.8			$ 564.5
Gross unrealized losses, less than twelve months	(1.3)	(24.9)			(11.6)
Over 12 months, Fair Market Value	455.6	299.1			16
Over 12 months, Gross Unrealized Losses	(83)	(62.8)			(0.4)
Total, Fair Market Value	474	501.9			580.5
Total, Gross Unrealized Losses	$ (84.3)	$ (87.7)			$ (12)
Number of Securities | security	214		220		116

Investments - Additional Inform

Investments - Additional Information (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 05, 2022	Apr. 01, 2022	Sep. 30, 2021	Dec. 23, 2019	Dec. 20, 2017	Jan. 01, 2017
Gain (Loss) on Securities [Line Items]
Catastrophe bonds, trading, cost		$ 2.4		$ 2.9	$ 3.4
Investment in the period		0.4		2	3.2
Equity method investment, aggregate cost		7		6.2	3.9	$ 0.9
Other investments, at fair value (2)		213.4		221.3	151.3
Restricted assets		266.5		471.3	539.8
Investment in Multiline reinsurer				0	0.5
Investment funded		0		0
Available-for-sale investment, allowance for credit loss, increase (decrease)		(3.7)		5	2.5
Investment, Identifier [Axis]: Unfunded Commitment, Apollo Real Estate Fund
Gain (Loss) on Securities [Line Items]
Unfunded commitment		5.3		5.3
Investment, Identifier [Axis]: Unfunded Commitment, Infrastructure fund
Gain (Loss) on Securities [Line Items]
Unfunded commitment		6.4		8.4
Investment, Identifier [Axis]: Unfunded Commitment, Real Estate Fund (Sept 2021)
Gain (Loss) on Securities [Line Items]
Unfunded commitment		3.3		3.3
Fair Value, Recurring [Member] | Apollo real estate fund
Gain (Loss) on Securities [Line Items]
Other investments, at fair value (2)		22.9		25.3
Real estate fund | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		213.4		221.3	151.3
Commercial mortgage loans
Gain (Loss) on Securities [Line Items]
Fair market value, trading		295		312.1	211.5
Middle market loans
Gain (Loss) on Securities [Line Items]
Fair market value, trading		102.1		106.9	65.4
Privately-held investments
Gain (Loss) on Securities [Line Items]
Fair market value, trading		482.4		533	307.1
Real estate fund (Dec 2017) | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		125.2		134.6	129.9
Real estate fund (Sept 2021) | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		39.2		40.6	21.4
Infrastructure fund | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		11.7		8.2
MVI
Gain (Loss) on Securities [Line Items]
Investment in the period	$ 0.8	0		0.4	0.4
Equity method investment, aggregate cost		0.8		0.8	0.5	0
Gross realized and unrealized gains (loss)				0	0.1	(0.4)
Investment in Multiline reinsurer				0	0
Digital Re
Gain (Loss) on Securities [Line Items]
Investment in the period		0		0	0.3
Equity method investment, ownership percentage												49%
Equity method investment, aggregate cost		0.2		0.2	0.2	0.4						$ 2.3
Gross realized and unrealized gains (loss)				0	0	(0.3)
Investment in Multiline reinsurer				0	0.5
Multi-Line Insurer
Gain (Loss) on Securities [Line Items]
Investment in the period		0.4		1.6	2.5
Equity method investment, aggregate cost		6		5.2	3.2	0.5
Other investments, at fair value (2)										$ 5
Gross realized and unrealized gains (loss)		0.4	$ 0.1	(0.4)	0.2	$ 0
Investment in Multiline reinsurer				0	0
Limited Partner | Real estate fund
Gain (Loss) on Securities [Line Items]
Other investments, at fair value (2)		$ 213.4		$ 221.3	$ 151.3
Restricted assets								$ 10	$ 20		$ 100
Limited Partner | Real estate fund | Apollo real estate fund
Gain (Loss) on Securities [Line Items]
Restricted assets								$ 30
Limited Partner | Infrastructure fund
Gain (Loss) on Securities [Line Items]
Restricted assets							$ 15

Variable Interest Entities - Na

Variable Interest Entities - Narrative (Details) - Investment	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Number of investments in VIEs	1	1

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets Measured on Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Catastrophe Bonds, Fair Value Disclosure	$ 2.4	$ 5.1	$ 5.3
Derivatives at fair value	17.2	56.2	12.9
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	6,245.6	6,100.9	6,512.6
Recurring | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value	17.2	56.2	12.9
Recurring | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(13.4)	(3.2)	(13.3)
Recurring | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(23.4)	(31.7)
Recurring | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	5.7	5.6
Recurring | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3,908.2	3,788.6	4,881.6
Recurring | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	169.3	52	10.1
Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,478.5	1,475.5	1,157.5
Privately-held Investments, at fair value	482.4	533	307.1
Catastrophe Bonds, Fair Value Disclosure	2.4	2.9	3.4
Recurring | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	11	6.3	2
Recurring | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	213.4	221.3	151.3
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	1,632.5	1,428.7	1,384.5
Recurring | Level 1 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value		0	0
Recurring | Level 1 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0	0
Recurring | Level 1 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0
Recurring | Level 1 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Recurring | Level 1 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,206.5	1,098.3	1,248.7
Recurring | Level 1 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	169.2	51.9	6.5
Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	247.7	272.2	128.2
Privately-held Investments, at fair value	0	0	0
Catastrophe Bonds, Fair Value Disclosure	0	0	0
Recurring | Level 1 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.1	6.3	1.1
Recurring | Level 1 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	3,940.7	3,949.6	4,669.7
Recurring | Level 2 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value	17.2	56.2	12.9
Recurring | Level 2 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(13.4)	(3.2)	(13.3)
Recurring | Level 2 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0
Recurring | Level 2 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	5.7	5.6
Recurring | Level 2 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	2,701.7	2,690.3	3,632.9
Recurring | Level 2 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0.1	0.1	3.6
Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,230.8	1,203.3	1,029.3
Privately-held Investments, at fair value	0	0	0
Catastrophe Bonds, Fair Value Disclosure	2.4	2.9	3.4
Recurring | Level 2 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1.9	0	0.9
Recurring | Level 2 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	459	501.3	307.1
Recurring | Level 3 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value		0	0
Recurring | Level 3 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0	0
Recurring | Level 3 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(23.4)	(31.7)
Recurring | Level 3 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Recurring | Level 3 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Privately-held Investments, at fair value	482.4	533	307.1
Catastrophe Bonds, Fair Value Disclosure	0	0	0
Recurring | Level 3 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,013.8	953	1,084.3
U.S. government | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	235	261.6	116.3
U.S. government | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,013.8	953	1,084.3
U.S. government | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	235	261.6	116.3
U.S. government | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. agency | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	8.2	8.8	21.5
U.S. agency | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. agency | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	8.2	8.8	21.5
U.S. agency | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	149.5	149.5	82.6
Municipal | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3.1	3.6	4
Municipal | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	149.5	149.5	82.6
Municipal | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3.1	3.6	4
Municipal | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,875.9	1,845	2,208.3
Corporate | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	165.4	162.1	96.8
Corporate | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,875.9	1,845	2,208.3
Corporate | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	165.4	162.1	96.8
Corporate | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	110.9	110.4	136.8
Non-U.S. government-backed corporate | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.6	11.6	13.1
Non-U.S. government-backed corporate | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	110.9	110.4	136.8
Non-U.S. government-backed corporate | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.6	11.6	13.1
Non-U.S. government-backed corporate | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S government | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	269.2	213.6	250.7
Non-U.S government | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	34.1	30.4	34.5
Non-U.S government | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	192.7	145.3	164.4
Non-U.S government | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	12.7	10.6	11.9
Non-U.S government | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	76.5	68.3	86.3
Non-U.S government | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	21.4	19.8	22.6
Non-U.S government | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S government | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Asset-backed | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0.5
Asset-backed | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	924.6	896.5	785.7
Asset-backed | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Asset-backed | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Asset-backed | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0.5
Asset-backed | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	924.6	896.5	785.7
Asset-backed | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Asset-backed | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-agency commercial mortgage-backed securities | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		5.6	6.9
Non-agency commercial mortgage-backed securities | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Non-agency commercial mortgage-backed securities | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		5.6	6.9
Non-agency commercial mortgage-backed securities | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Agency mortgage-backed | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	475	502.7	1,090
Agency mortgage-backed | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	20.1	21.4	30.2
Agency mortgage-backed | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	475	502.7	1,090
Agency mortgage-backed | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	20.1	21.4	30.2
Agency mortgage-backed | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
High yield loans | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	86.6	88.3	76.9
High yield loans | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
High yield loans | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	86.6	88.3	76.9
High yield loans | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	$ 0	$ 0	$ 0

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements - Reconciliation of Level 3 Assets and Liabilities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Accumulated other comprehensive (loss)
Commercial mortgage loans
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	$ 312.1	$ 211.5
Balance at the end of the year	295	312.1	$ 211.5
Middle market loans
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.4
Balance at the end of the year	102.1	106.9	65.4
Equity securities
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6
Balance at the end of the year	12.1	6.6	3.6
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6
Balance at the end of the year		25.6
Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(13.7)	(4.6)	(2.2)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	533	307.1
Balance at the end of the year	482.4	533	307.1
Recurring | Level 3 | Liability
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	(31.7)	0
Liability purchases	0	(17.2)
Liability transfers	0	0
Liability sales	0	0
Liability, increase (decrease) in fv included in net income	8.3	(14.5)
Balance at the end of the period	(23.4)	(31.7)	0
Change in unrealized gains or losses	0	0
Recurring | Level 3 | Liability | Loss Portfolio Transfer
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	(31.7)	0
Liability purchases	0	(17.2)
Liability transfers	0	0
Liability sales	0	0
Liability, increase (decrease) in fv included in net income		(14.5)
Balance at the end of the period	(23.4)	(31.7)	0
Change in unrealized gains or losses	0	0
Recurring | Commercial mortgage loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(10.5)	(0.5)	(0.5)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	312.1	211.5
Balance at the end of the year	295	312.1	211.5
Recurring | Middle market loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(2)	(2.1)	(1.5)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.3
Balance at the end of the year	102.1	106.9	65.3
Recurring | Asset-backed | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(1.1)	(2)	(0.2)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	66.8	26.7
Balance at the end of the year	58.4	66.8	26.7
Recurring | Global corporate securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(0.1)	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	15
Balance at the end of the year	14.8	15
Recurring | Equity securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	0	0	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6
Balance at the end of the year	12.1	6.6	3.6
Recurring | Preference shares | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)			0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year		0
Balance at the end of the year			0
Recurring | Short-term investments | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	0	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6
Balance at the end of the year	0	25.6
Assets | Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	533	307.1	299.3
Purchases and issuances	23	378.2	205.1
Settlements and sales	(58.4)	(147.4)	(182)
Increase (decrease) in fair value included in net income	(8.5)	(4.9)	4.2
Balance at the end of the year		533	307.1
Transfers in/(out)	(6.7)	0	(19.5)
Assets | Recurring | Commercial mortgage loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	312.1	211.5	163.6
Purchases and issuances	15.9	215.7	169.9
Settlements and sales	(23.2)	(113.1)	(122.5)
Increase (decrease) in fair value included in net income	(9.8)	(2)	0.5
Balance at the end of the year		312.1	211.5
Transfers in/(out)	0	0	0
Assets | Recurring | Middle market loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.3	112.1
Purchases and issuances	0.1	61.8	5.6
Settlements and sales	(5.4)	(19.3)	(56.1)
Increase (decrease) in fair value included in net income	0.5	(0.9)	3.7
Balance at the end of the year		106.9	65.3
Transfers in/(out)	0	0	0
Assets | Recurring | Asset-backed | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	66.8	26.7	18.6
Purchases and issuances	0	54.5	10
Settlements and sales	(3.8)	(12.6)	(1.8)
Increase (decrease) in fair value included in net income	0.9	(1.8)	(0.1)
Balance at the end of the year		66.8	26.7
Transfers in/(out)	(5.5)	0	0
Assets | Recurring | Global corporate securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	15	0
Purchases and issuances	0	15.1
Settlements and sales	(0.2)	0
Increase (decrease) in fair value included in net income	0	(0.1)
Balance at the end of the year		15	0
Transfers in/(out)	0	0
Assets | Recurring | Equity securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6	5
Purchases and issuances	7	5.5	0.1
Settlements and sales	(0.2)	(2.4)	(1.6)
Increase (decrease) in fair value included in net income	(0.1)	(0.1)	0.1
Balance at the end of the year		6.6	3.6
Transfers in/(out)	(1.2)	0	0
Assets | Recurring | Preference shares | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year			0
Purchases and issuances			19.5
Settlements and sales			0
Increase (decrease) in fair value included in net income			0
Transfers in/(out)		0	(19.5)
Assets | Recurring | Short-term investments | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6	0
Purchases and issuances	0	25.6
Settlements and sales	(25.6)	0
Increase (decrease) in fair value included in net income	0	0
Balance at the end of the year		25.6	$ 0
Transfers in/(out)	$ 0	$ 0

Fair Value Measurements - Input

Fair Value Measurements - Inputs Used (Details) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Held for trading financial assets, at fair value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	482.4		533	307.1
Held for trading financial assets, at fair value | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 482.4		$ 533	$ 307.1
Discounted cash flow | Commercial mortgage loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.037		0.039
Discounted cash flow | Commercial mortgage loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.112		0.094
Discounted cash flow | Commercial mortgage loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.062		0.053
Discounted cash flow | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 270		$ 200.7
Discounted cash flow | Middle market loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.058		0.074
Discounted cash flow | Middle market loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.093		0.185
Discounted cash flow | Middle market loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.068		0.099
Discounted cash flow | Middle market loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 58.4		$ 106.9
Discounted cash flow | Asset-backed | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.064		0.058
Discounted cash flow | Asset-backed | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.074		0.093
Discounted cash flow | Asset-backed | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.064		0.067
Discounted cash flow | Asset-backed | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 14.8
Discounted cash flow | Global corporate securities | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 12.1		$ 15
Discounted cash flow | Equity securities — Trading | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.090
Discounted cash flow | Equity securities — Trading | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.125
Discounted cash flow | Equity securities — Trading | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.091
Discounted cash flow | Equity securities — Trading | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			$ 5.3
Discounted cash flow | Short-term investments | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.064
Discounted cash flow | Short-term investments | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.064
Discounted cash flow | Short-term investments | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs			0.064
Discounted cash flow | Short-term investments | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			$ 25.6
Transaction value | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 25		85.8
Transaction value | Equity securities — Trading | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			1.3
Liquidation method | Commercial mortgage loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.076
Liquidation method | Commercial mortgage loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.209
Liquidation method | Commercial mortgage loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.108
Liquidation method | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			25.6
Recovery approach | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 102.1
Recovery approach | Asset-backed | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			$ 66.8

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) quotesPerInvestment	Dec. 31, 2022 USD ($) quotesPerInvestment	Dec. 31, 2021 USD ($) quotesPerInvestment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Quotes per fixed income investment | quotesPerInvestment	2.8	2.9	3
Assets | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers in/(out)	$ (6.7)	$ 0	$ (19.5)
Settlements and sales	(58.4)	(147.4)	(182)
Held for trading financial assets, at fair value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	482.4	533	307.1
Held for trading financial assets, at fair value | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 482.4	$ 533	$ 307.1

Reinsurance - Summary of Assume

Reinsurance - Summary of Assumed and Ceded Reinsurance on Premiums Written, Premiums Earned and Insurance Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premiums written:
Direct	$ 1,249.5	$ 1,305.7	$ 2,531.7	$ 2,341.4	$ 2,042.1
Assumed	875.7	1,045.6	1,807	1,597	1,656.4
Ceded	(774.7)	(845.2)	(1,442.7)	(1,350.7)	(1,120.7)
Net premiums written	1,350.5	1,506.1	2,896	2,587.7	2,577.8
Premiums earned:
Direct	1,203.6	1,171.5	2,370.8	2,139.1	2,026.4
Assumed	755.7	776.9	1,617.2	1,479.2	1,612
Ceded	(671.9)	(621.2)	(1,299.3)	(1,207.8)	(1,110.9)
Net premiums earned	1,287.4	1,327.2	2,688.7	2,410.5	2,527.5
Insurance losses and loss adjustment expenses:
Direct	691.7	719.2	1,574.2	1,499.8	1,479.6
Assumed	353.4	402.4	939.5	1,000.6	1,134.5
Ceded	(328)	(353.9)	(833.7)	(807.1)	(773.3)
Net insurance losses and loss adjustment expenses	$ 717.1	$ 767.7	$ 1,680	$ 1,693.3	$ 1,840.8

Reinsurance - Additional Inform

Reinsurance - Additional Information (Details) - USD ($) $ in Millions			6 Months Ended	12 Months Ended
	Oct. 01, 2022	Jan. 10, 2022	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	May 30, 2022	Dec. 31, 2020	Mar. 02, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year			$ 4,658	$ 4,897.7	$ 3,298.1	$ 5,006.5		$ 3,195.2
Reinsurance Recoverable, Allowance for Credit Loss			3.3	3.7	3.3			$ 3.8
Reinsurance Recoverable, Allowance for Credit Loss, Period Increase (Decrease)			$ (0.4)	$ 0.4	$ (0.5)
Reinsurance Contracts [Axis]: Funds withheld credited with interest for periods after October 1, 2022
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance Retention Policy, Retrocession Premium, Interest Rate	1.75%
Reinsurance Contracts [Axis]: LPT
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverables, premium paid and recognized							$ 1,840.1
Enstar
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year									$ 770
Enstar | Reinsurance Contracts [Axis]: LPT losses reinsured]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year									$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT net losses reinsured
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Event		$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT premium paid
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance Recoverables for Unpaid Claims and Claims Adjustment, Ceded Claims Gross		3,160
Maximum | Reinsurance Contracts [Axis]: Loss Portfolio Transfer Agreement Limit
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance, Amount Retained, Per Event		$ 3,570

Derivative Contracts - Fair Val

Derivative Contracts - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 1,884	$ 1,675.3	$ 1,545.7
Cash collateral	2.7	3.7	2.1
Not Designated as Hedging Instrument | Derivatives at Fair Value | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	7.2	41.9	12.9
Derivative, Notional Amount	670.6	945.8	759.8
Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	(13.4)	(3.2)	(12.4)
Derivative, Notional Amount	1,213.4	729.5	785.9
Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Embedded Derivative Financial Instruments
Derivatives, Fair Value [Line Items]
Fair Value	(23.4)	(31.7)	0
Derivative, Notional Amount	0	0	0
Designated as Hedging Instrument | Derivatives at Fair Value | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	10	14.3	0
Derivative, Notional Amount	$ 54.7	109.7	0
Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value		0	(0.9)
Derivative, Notional Amount		$ 0	$ 143.1

Derivative Contracts - Gain_(Lo

Derivative Contracts - Gain/(Loss) Recognized in Income on Derivative (Details) - Foreign exchange contracts - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Not Designated as Hedging Instrument | Gain (loss) on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to net income from derivative instruments	$ 19.6	$ (84.9)	$ (80.5)	$ (35.9)
Designated as Hedging Instrument | General, administrative and corporate expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	(3.7)	2.8	5.9	(5.7)
Designated as Hedging Instrument | Net change from current period hedged transactions
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	$ (4.3)	$ (6.4)	$ 15.4	$ (6.2)

Derivative Contracts - Addition

Derivative Contracts - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Level 3 | Liability | Fair Value, Recurring [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Liability, increase (decrease) in fv included in net income	$ 8.3		$ (14.5)
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange	1,884		1,675.3	$ 1,545.7
Foreign exchange contracts | Not Designated as Hedging Instrument | Derivative At Fair Value
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange	670.6		945.8	759.8
Foreign exchange contracts | Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange	1,213.4		729.5	785.9
Foreign exchange contracts | Designated as Hedging Instrument | Derivative At Fair Value
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange	54.7		109.7	0
Foreign exchange contracts | Designated as Hedging Instrument | Liabilities Under Derivative Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange			0	143.1
Foreign exchange contracts | Net change from current period hedged transactions | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	(4.3)	$ (6.4)	15.4	(6.2)
Foreign exchange contracts | General, administrative and corporate expenses | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	(3.7)	2.8	5.9	(5.7)
Foreign exchange contracts | Gain (loss) on derivative instruments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to net income from derivative instruments	$ 19.6	$ (84.9)	(80.5)	$ (35.9)
Loss Portfolio Transfer | Level 3 | Liability | Fair Value, Recurring [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Liability, increase (decrease) in fv included in net income			$ (14.5)

Deferred Policy Acquisition C_3

Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance at the beginning of the period	$ 319	$ 290.8	$ 290.8	$ 306.6
Acquisition costs deferred			460	398.3
Amortization of deferred acquisition costs	(192.9)	$ (216.5)	(431.8)	(414.1)	$ (465.7)
Balance at the end of the period	$ 353.1		$ 319	$ 290.8	$ 306.6

Reserves for Losses and Adjus_5

Reserves for Losses and Adjustment Expenses - Reconciliation of Beginning and Ending Consolidated Loss and Loss Adjustment Expenses (LAE) Reserves (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
	Jan. 10, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 30, 2022	Mar. 02, 2020	Dec. 31, 2019
Insurance [Abstract]
Provision for losses and LAE, beginning balance		$ 7,710.9	$ 7,611.8	$ 7,611.8	$ 7,165.3	$ 6,951.8
Less reinsurance recoverable				(4,897.7)	(3,298.1)	(3,195.2)			$ (2,319.8)
Net losses and LAE reserves, beginning balance		2,813.2	4,313.7	4,313.7	3,970.1	4,632
Movement in net provision for losses and LAE for claims incurred:
Current year		723.5	775	1,651.9	1,648.2	1,841.7
Prior years		(6.4)	(7.3)	28.1	45.1	(0.9)
Total incurred		717.1	767.7	1,680	1,693.3	1,840.8
Net Losses and LAE payments for claims incurred:
Current year		(30.8)	(35.5)	(192.7)	(729.1)	(404.9)
Prior years		(438.6)	(616.9)	(1,098.4)	(580.7)	(1,359.7)
Total paid		(469.4)	(652.4)	(1,291.1)	(1,309.8)	(1,764.6)
Foreign exchange (gains)/losses		22	(83.6)	(49.3)	(39.9)	80.4
Net losses and LAE reserves, ending balance		3,082.9	2,505.3	2,813.2	4,313.7	3,970.1
Plus reinsurance recoverable on unpaid losses at the end of the year		4,658	5,006.5	4,897.7	3,298.1	3,195.2
Provision for losses and LAE at the end of the year		7,740.9	7,511.8	7,710.9	7,611.8	7,165.3
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Net loss and LAE expenses disposed (1)		0	1,840.1	1,840.1	0	818.5
Reinsurance Contracts [Axis]: LPT
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable total							$ 2,610.1
Insurance
Insurance [Abstract]
Provision for losses and LAE, beginning balance		1,452.5	2,165.3	2,165.3	1,874.4
Net losses and LAE reserves, beginning balance		1,452.5	2,165.3	2,165.3	1,874.4
Movement in net provision for losses and LAE for claims incurred:
Prior years		8.5		86.9
Net Losses and LAE payments for claims incurred:
Net losses and LAE reserves, ending balance				1,452.5	2,165.3	1,874.4
Provision for losses and LAE at the end of the year		1,641.7	$ 1,314.9	$ 1,452.5	2,165.3	$ 1,874.4
Insurance | Reinsurance Contracts [Axis]: LPT, deferred gain
Movement in net provision for losses and LAE for claims incurred:
Prior years		13.2
Insurance | Reinsurance Contracts [Axis]: LPT, offset post-LPT years
Movement in net provision for losses and LAE for claims incurred:
Prior years		$ 4.7
Surety Product Line | Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Net loss and LAE expenses disposed (1)					(42)
Accident and Health Insurance Product Line
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Net loss and LAE expenses disposed (1)					$ (6.5)
Enstar
Net Losses and LAE payments for claims incurred:
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 770
Enstar | Reinsurance Contracts [Axis]: LPT losses reinsured]
Net Losses and LAE payments for claims incurred:
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT net losses reinsured
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Event	$ 3,120

Reserves for Losses and Adjus_6

Reserves for Losses and Adjustment Expenses - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Insurance [Abstract]
Provision for losses and LAE for claims incurred	$ (6.4)	$ (7.3)	$ 28.1	$ 45.1	$ (0.9)
Prior years	(6.4)	(7.3)	28.1	45.1	(0.9)
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	(6.4)	$ (7.3)	28.1	$ 45.1	$ (0.9)
Reinsurance
Insurance [Abstract]
Provision for losses and LAE for claims incurred	(2.1)
Prior years	(2.1)
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	(2.1)
Insurance
Insurance [Abstract]
Provision for losses and LAE for claims incurred	8.5		86.9
Prior years	8.5		86.9
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	$ 8.5		$ 86.9

Reserves for Losses and Adjus_7

Reserves for Losses and Adjustment Expenses - Reconciliation of Reinsurance Recoverables on Unpaid Losses (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 30, 2022
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance	$ 4,897.7	$ 3,298.1	$ 3,298.1
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance, Ending Balance			4,897.7	$ 3,298.1
Provision for losses and LAE for claims incurred	(6.4)	(7.3)	28.1	45.1	$ (0.9)
Reinsurance Contracts [Axis]: LPT
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverables, premium paid and recognized						$ 1,840.1
Reinsurance Contracts [Axis]: Retroactive Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance	2,132	$ 838.1	838.1
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance, Ending Balance	$ 1,877.3		$ 2,132	$ 838.1

Reserves for Losses and Adjus_8

Reserves for Losses and Adjustment Expenses Short-duration Insurance Contracts, Claims by Accident Year (Details)	Dec. 31, 2022 USD ($) Integer	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance	$ 3,151,600,000	$ 4,484,000,000
Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	1,772,500,000
Cumulative paid claims and allocated claim adjustment expense, Net	1,513,500,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	259,000,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	259,000,000	289,300,000
Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	1,417,100,000
Cumulative paid claims and allocated claim adjustment expense, Net	959,800,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	457,300,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	457,300,000	725,600,000
Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	1,929,200,000
Cumulative paid claims and allocated claim adjustment expense, Net	1,765,500,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	163,700,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	163,700,000	427,900,000
Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	1,970,000,000
Cumulative paid claims and allocated claim adjustment expense, Net	1,298,100,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	671,900,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	671,900,000	808,700,000
Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	2,854,500,000
Cumulative paid claims and allocated claim adjustment expense, Net	2,176,600,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	677,900,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	677,900,000	784,900,000
Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	1,628,700,000
Cumulative paid claims and allocated claim adjustment expense, Net	1,057,100,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	571,600,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	571,600,000	975,300,000
Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	2,344,800,000
Cumulative paid claims and allocated claim adjustment expense, Net	1,994,600,000
All outstanding liabilities for 2013 and subsequent years, net of reinsurance	350,200,000
All outstanding liabilities before 2013, net of reinsurance	0
Liability for claims and claim adjustment expenses, net of reinsurance	350,200,000	472,300,000
Accident Year 2013 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	106,100,000	102,100,000	$ 109,500,000	$ 109,300,000	$ 109,000,000	$ 110,900,000	$ 109,900,000	$ 114,200,000	$ 114,400,000	$ 126,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	0
Cumulative paid claims and allocated claim adjustment expense, Net	$ 106,100,000	106,800,000	107,900,000	107,600,000	105,800,000	103,000,000	98,600,000	86,800,000	73,700,000	37,500,000
Accident Year 2013 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	86,700,000	107,800,000	100,000,000	101,400,000	101,100,000	99,800,000	116,800,000	111,600,000	112,800,000	128,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	3,392
Cumulative paid claims and allocated claim adjustment expense, Net	$ 86,700,000	84,000,000	83,900,000	82,000,000	77,900,000	65,900,000	51,200,000	38,200,000	25,100,000	2,100,000
Accident Year 2013 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	319,700,000	346,500,000	338,700,000	343,600,000	345,000,000	331,500,000	324,300,000	340,700,000	332,100,000	319,400,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,179
Cumulative paid claims and allocated claim adjustment expense, Net	$ 319,700,000	309,000,000	309,300,000	299,100,000	283,100,000	263,500,000	234,100,000	203,900,000	130,900,000	41,200,000
Accident Year 2013 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	82,900,000	101,000,000	95,100,000	88,800,000	89,900,000	98,600,000	99,600,000	103,100,000	98,700,000	104,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	606
Cumulative paid claims and allocated claim adjustment expense, Net	$ 82,900,000	79,900,000	76,400,000	73,200,000	71,100,000	62,800,000	64,600,000	30,600,000	20,600,000	7,900,000
Accident Year 2013 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	156,300,000	159,500,000	162,900,000	165,800,000	168,500,000	171,700,000	173,100,000	184,100,000	193,700,000	212,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	832
Cumulative paid claims and allocated claim adjustment expense, Net	$ 156,300,000	156,000,000	156,000,000	161,600,000	160,100,000	158,600,000	154,100,000	142,600,000	95,700,000	33,900,000
Accident Year 2013 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	151,900,000	191,600,000	197,900,000	200,300,000	197,700,000	202,300,000	219,100,000	221,600,000	226,700,000	211,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,700
Cumulative paid claims and allocated claim adjustment expense, Net	$ 151,900,000	144,200,000	137,900,000	126,000,000	113,500,000	91,800,000	64,400,000	42,300,000	15,700,000	3,400,000
Accident Year 2013 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	98,100,000	104,800,000	108,300,000	111,600,000	111,900,000	115,700,000	116,300,000	127,700,000	135,700,000	140,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	579
Cumulative paid claims and allocated claim adjustment expense, Net	$ 98,100,000	98,100,000	99,000,000	99,300,000	98,400,000	98,400,000	91,400,000	84,400,000	68,700,000	$ 24,300,000
Accident Year 2014 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	131,100,000	125,200,000	130,100,000	130,700,000	132,200,000	133,000,000	132,400,000	154,900,000	162,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	9,949
Cumulative paid claims and allocated claim adjustment expense, Net	$ 131,100,000	129,900,000	128,700,000	127,300,000	126,000,000	122,000,000	112,500,000	85,200,000	39,900,000
Accident Year 2014 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	107,400,000	137,900,000	131,800,000	134,900,000	131,000,000	124,000,000	134,200,000	122,600,000	139,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	3,914
Cumulative paid claims and allocated claim adjustment expense, Net	$ 107,400,000	104,000,000	105,400,000	93,100,000	70,100,000	57,300,000	31,500,000	12,600,000	2,500,000
Accident Year 2014 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	279,100,000	317,600,000	300,700,000	311,400,000	304,500,000	308,900,000	297,200,000	312,200,000	308,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,058
Cumulative paid claims and allocated claim adjustment expense, Net	$ 279,100,000	274,200,000	261,700,000	249,500,000	231,300,000	208,600,000	188,100,000	116,000,000	53,200,000
Accident Year 2014 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	118,900,000	124,300,000	118,800,000	118,000,000	128,900,000	117,700,000	127,400,000	128,800,000	133,200,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	794
Cumulative paid claims and allocated claim adjustment expense, Net	$ 118,900,000	102,300,000	90,900,000	84,000,000	78,500,000	71,100,000	52,700,000	30,200,000	2,800,000
Accident Year 2014 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	138,100,000	140,100,000	141,200,000	141,100,000	145,900,000	145,700,000	157,100,000	172,600,000	185,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	900
Cumulative paid claims and allocated claim adjustment expense, Net	$ 138,100,000	137,800,000	137,600,000	136,000,000	137,400,000	133,700,000	124,400,000	98,500,000	36,900,000
Accident Year 2014 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	144,700,000	191,100,000	198,000,000	202,100,000	199,000,000	205,500,000	212,300,000	204,000,000	201,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,843
Cumulative paid claims and allocated claim adjustment expense, Net	$ 144,700,000	133,000,000	123,400,000	105,900,000	85,400,000	59,600,000	37,400,000	13,600,000	2,500,000
Accident Year 2014 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	105,400,000	116,600,000	118,000,000	122,200,000	123,600,000	120,800,000	129,500,000	137,500,000	149,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	622
Cumulative paid claims and allocated claim adjustment expense, Net	$ 105,400,000	104,400,000	102,500,000	100,900,000	98,000,000	87,800,000	79,800,000	55,200,000	$ 16,200,000
Accident Year 2015 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	189,200,000	179,600,000	193,900,000	196,900,000	196,300,000	193,900,000	199,000,000	233,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	11,549
Cumulative paid claims and allocated claim adjustment expense, Net	$ 189,200,000	190,400,000	188,900,000	190,100,000	174,100,000	165,100,000	138,300,000	56,300,000
Accident Year 2015 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	197,200,000	250,400,000	228,300,000	230,100,000	197,500,000	180,500,000	217,900,000	197,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,775
Cumulative paid claims and allocated claim adjustment expense, Net	$ 197,200,000	174,500,000	163,600,000	135,000,000	90,200,000	55,100,000	16,400,000	3,000,000
Accident Year 2015 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	302,700,000	327,300,000	309,900,000	307,200,000	283,700,000	279,300,000	297,000,000	295,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,076
Cumulative paid claims and allocated claim adjustment expense, Net	$ 302,700,000	277,500,000	255,500,000	220,000,000	192,100,000	172,700,000	122,500,000	44,600,000
Accident Year 2015 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	163,900,000	189,900,000	183,000,000	188,000,000	187,100,000	183,100,000	173,400,000	171,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,085
Cumulative paid claims and allocated claim adjustment expense, Net	$ 163,900,000	144,100,000	137,600,000	108,800,000	88,600,000	69,500,000	43,100,000	13,500,000
Accident Year 2015 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	160,600,000	177,200,000	168,900,000	168,900,000	153,500,000	173,800,000	183,700,000	210,000,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,048
Cumulative paid claims and allocated claim adjustment expense, Net	$ 160,600,000	159,500,000	155,900,000	153,600,000	136,700,000	124,200,000	93,600,000	35,600,000
Accident Year 2015 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	135,100,000	198,800,000	203,700,000	207,500,000	209,800,000	207,300,000	197,600,000	191,100,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	2,038
Cumulative paid claims and allocated claim adjustment expense, Net	$ 135,100,000	121,400,000	107,300,000	88,400,000	64,700,000	37,800,000	17,500,000	3,300,000
Accident Year 2015 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	132,500,000	150,000,000	150,000,000	154,500,000	155,900,000	161,100,000	166,400,000	163,200,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	774
Cumulative paid claims and allocated claim adjustment expense, Net	$ 132,500,000	131,700,000	131,700,000	128,700,000	119,900,000	102,500,000	55,200,000	$ 17,300,000
Accident Year 2016 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	244,800,000	233,400,000	242,500,000	241,300,000	240,000,000	245,000,000	233,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	10,773
Cumulative paid claims and allocated claim adjustment expense, Net	$ 244,800,000	233,700,000	228,600,000	219,200,000	198,100,000	166,100,000	65,700,000
Accident Year 2016 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	163,300,000	247,400,000	195,100,000	184,200,000	177,600,000	182,500,000	211,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,818
Cumulative paid claims and allocated claim adjustment expense, Net	$ 163,300,000	128,800,000	106,100,000	79,700,000	38,600,000	22,000,000	4,000,000
Accident Year 2016 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	199,200,000	224,300,000	217,700,000	227,900,000	227,500,000	229,000,000	258,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,431
Cumulative paid claims and allocated claim adjustment expense, Net	$ 199,200,000	197,300,000	189,500,000	163,100,000	141,300,000	81,900,000	30,800,000
Accident Year 2016 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	163,200,000	189,000,000	182,900,000	199,700,000	213,700,000	209,300,000	188,400,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,244
Cumulative paid claims and allocated claim adjustment expense, Net	$ 163,200,000	133,800,000	124,600,000	128,700,000	100,700,000	70,700,000	14,800,000
Accident Year 2016 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	229,800,000	230,100,000	237,700,000	242,100,000	263,200,000	264,600,000	264,200,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,307
Cumulative paid claims and allocated claim adjustment expense, Net	$ 229,800,000	230,700,000	224,400,000	211,600,000	200,900,000	160,500,000	55,800,000
Accident Year 2016 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	174,600,000	258,500,000	258,500,000	251,000,000	241,000,000	241,400,000	229,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	2,153
Cumulative paid claims and allocated claim adjustment expense, Net	$ 174,600,000	145,300,000	124,600,000	94,800,000	62,900,000	32,900,000	8,900,000
Accident Year 2016 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	197,600,000	218,800,000	222,600,000	227,600,000	234,600,000	236,600,000	235,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	938
Cumulative paid claims and allocated claim adjustment expense, Net	$ 197,600,000	201,800,000	191,800,000	181,700,000	163,900,000	149,500,000	$ 58,200,000
Accident Year 2017 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	247,700,000	280,900,000	248,100,000	246,800,000	253,700,000	290,400,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	9,717
Cumulative paid claims and allocated claim adjustment expense, Net	$ 247,700,000	242,100,000	237,900,000	217,200,000	185,000,000	95,000,000
Accident Year 2017 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	154,400,000	234,600,000	190,500,000	173,400,000	169,900,000	176,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	5,495
Cumulative paid claims and allocated claim adjustment expense, Net	$ 154,400,000	110,300,000	93,400,000	51,200,000	22,300,000	3,400,000
Accident Year 2017 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	205,300,000	231,500,000	213,700,000	206,200,000	199,900,000	209,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	6,059
Cumulative paid claims and allocated claim adjustment expense, Net	$ 205,300,000	155,700,000	167,600,000	139,600,000	97,000,000	40,000,000
Accident Year 2017 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	166,700,000	208,800,000	185,200,000	184,500,000	179,600,000	203,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,737
Cumulative paid claims and allocated claim adjustment expense, Net	$ 166,700,000	135,600,000	116,200,000	83,000,000	51,000,000	27,100,000
Accident Year 2017 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	447,700,000	595,500,000	500,400,000	511,700,000	529,400,000	550,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,953
Cumulative paid claims and allocated claim adjustment expense, Net	$ 447,700,000	433,700,000	437,100,000	413,500,000	355,400,000	123,000,000
Accident Year 2017 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	147,700,000	265,500,000	248,900,000	249,700,000	239,100,000	241,000,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	2,166
Cumulative paid claims and allocated claim adjustment expense, Net	$ 147,700,000	115,700,000	96,500,000	58,500,000	30,200,000	8,700,000
Accident Year 2017 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	325,900,000	364,200,000	361,100,000	372,100,000	388,400,000	375,400,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,336
Cumulative paid claims and allocated claim adjustment expense, Net	$ 325,900,000	314,400,000	303,800,000	268,900,000	237,400,000	$ 94,100,000
Accident Year 2018 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	177,300,000	196,200,000	182,200,000	198,100,000	196,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	8,308
Cumulative paid claims and allocated claim adjustment expense, Net	$ 177,300,000	173,000,000	176,100,000	153,600,000	60,300,000
Accident Year 2018 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	94,400,000	169,700,000	132,200,000	122,500,000	119,400,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	5,500
Cumulative paid claims and allocated claim adjustment expense, Net	$ 94,400,000	65,500,000	41,400,000	27,200,000	3,000,000
Accident Year 2018 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	169,700,000	238,800,000	207,900,000	207,100,000	170,100,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	5,153
Cumulative paid claims and allocated claim adjustment expense, Net	$ 169,700,000	154,700,000	132,600,000	104,300,000	26,700,000
Accident Year 2018 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	125,400,000	163,200,000	151,200,000	169,400,000	153,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	4,643
Cumulative paid claims and allocated claim adjustment expense, Net	$ 125,400,000	113,300,000	97,800,000	71,600,000	17,400,000
Accident Year 2018 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	304,500,000	571,000,000	356,000,000	362,800,000	323,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,780
Cumulative paid claims and allocated claim adjustment expense, Net	$ 304,500,000	315,300,000	296,800,000	290,100,000	122,100,000
Accident Year 2018 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	130,400,000	264,300,000	262,500,000	255,000,000	226,000,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	2,002
Cumulative paid claims and allocated claim adjustment expense, Net	$ 130,400,000	103,800,000	73,000,000	33,200,000	7,100,000
Accident Year 2018 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	342,100,000	419,500,000	390,300,000	391,900,000	392,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,403
Cumulative paid claims and allocated claim adjustment expense, Net	$ 342,100,000	328,500,000	312,200,000	279,000,000	$ 26,700,000
Accident Year 2019 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	107,800,000	104,100,000	126,500,000	122,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	6,852
Cumulative paid claims and allocated claim adjustment expense, Net	$ 107,800,000	99,300,000	88,600,000	48,000,000
Accident Year 2019 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	88,300,000	155,300,000	144,400,000	122,000,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	5,198
Cumulative paid claims and allocated claim adjustment expense, Net	$ 88,300,000	68,000,000	16,700,000	6,200,000
Accident Year 2019 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	124,000,000	151,100,000	152,800,000	145,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	3,662
Cumulative paid claims and allocated claim adjustment expense, Net	$ 124,000,000	117,500,000	72,400,000	33,400,000
Accident Year 2019 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	195,200,000	253,900,000	259,600,000	246,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	23,831
Cumulative paid claims and allocated claim adjustment expense, Net	$ 195,200,000	136,800,000	86,200,000	26,800,000
Accident Year 2019 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	203,600,000	358,700,000	249,600,000	237,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,399
Cumulative paid claims and allocated claim adjustment expense, Net	$ 203,600,000	191,400,000	143,900,000	28,100,000
Accident Year 2019 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	82,100,000	252,000,000	253,100,000	232,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,567
Cumulative paid claims and allocated claim adjustment expense, Net	$ 82,100,000	60,900,000	36,200,000	9,100,000
Accident Year 2019 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	423,600,000	397,400,000	493,400,000	470,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Number of Reported Claims | Integer	1,537
Cumulative paid claims and allocated claim adjustment expense, Net	$ 423,600,000	398,800,000	379,600,000	$ 272,500,000
Accident Year 2020 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	205,100,000	195,900,000	199,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 24,400,000
Number of Reported Claims | Integer	7,542
Cumulative paid claims and allocated claim adjustment expense, Net	$ 150,100,000	122,900,000	60,100,000
Accident Year 2020 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	138,700,000	139,300,000	131,100,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 72,100,000
Number of Reported Claims | Integer	3,755
Cumulative paid claims and allocated claim adjustment expense, Net	$ 36,100,000	9,200,000	0
Accident Year 2020 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	125,700,000	111,200,000	110,200,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 17,500,000
Number of Reported Claims | Integer	3,856
Cumulative paid claims and allocated claim adjustment expense, Net	$ 88,600,000	66,400,000	28,500,000
Accident Year 2020 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	336,200,000	346,200,000	346,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 118,000,000
Number of Reported Claims | Integer	105,947
Cumulative paid claims and allocated claim adjustment expense, Net	$ 174,200,000	120,800,000	47,200,000
Accident Year 2020 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	348,900,000	402,100,000	317,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 81,000,000
Number of Reported Claims | Integer	1,379
Cumulative paid claims and allocated claim adjustment expense, Net	$ 237,300,000	165,500,000	41,800,000
Accident Year 2020 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	197,900,000	233,600,000	252,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 123,200,000
Number of Reported Claims | Integer	1,088
Cumulative paid claims and allocated claim adjustment expense, Net	$ 44,100,000	27,600,000	9,100,000
Accident Year 2020 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	374,100,000	600,000,000	412,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 53,100,000
Number of Reported Claims | Integer	1,470
Cumulative paid claims and allocated claim adjustment expense, Net	$ 290,400,000	269,600,000	$ 212,800,000
Accident Year 2021 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	199,500,000	204,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 38,200,000
Number of Reported Claims	6,583
Cumulative paid claims and allocated claim adjustment expense, Net	$ 118,600,000	58,200,000
Accident Year 2021 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	185,600,000	170,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 119,700,000
Number of Reported Claims	3,356
Cumulative paid claims and allocated claim adjustment expense, Net	$ 8,800,000	3,000,000
Accident Year 2021 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	96,100,000	93,000,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,300,000
Number of Reported Claims	4,863
Cumulative paid claims and allocated claim adjustment expense, Net	$ 52,300,000	23,500,000
Accident Year 2021 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	302,800,000	284,500,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 170,400,000
Number of Reported Claims	34,942
Cumulative paid claims and allocated claim adjustment expense, Net	$ 90,200,000	42,800,000
Accident Year 2021 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	472,700,000	647,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 196,900,000
Number of Reported Claims | Integer	1,411
Cumulative paid claims and allocated claim adjustment expense, Net	$ 233,200,000	75,000,000
Accident Year 2021 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	215,600,000	205,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 135,900,000
Number of Reported Claims | Integer	815
Cumulative paid claims and allocated claim adjustment expense, Net	$ 37,100,000	7,800,000
Accident Year 2021 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	151,600,000	156,600,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 55,800,000
Number of Reported Claims | Integer	1,276
Cumulative paid claims and allocated claim adjustment expense, Net	$ 53,200,000	$ 28,200,000
Accident Year 2022 | Property Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	163,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 62,900,000
Number of Reported Claims	4,171
Cumulative paid claims and allocated claim adjustment expense, Net	$ 40,800,000
Accident Year 2022 | Casualty Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	201,100,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 132,100,000
Number of Reported Claims	2,709
Cumulative paid claims and allocated claim adjustment expense, Net	$ 23,200,000
Accident Year 2022 | Marine, Aviation and Energy Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	107,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 58,800,000
Number of Reported Claims	3,810
Cumulative paid claims and allocated claim adjustment expense, Net	$ 24,900,000
Accident Year 2022 | Financial and Professional Insurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	314,800,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 265,200,000
Number of Reported Claims	3,487
Cumulative paid claims and allocated claim adjustment expense, Net	$ 17,500,000
Accident Year 2022 | Property Catastrophe and Other Property Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	392,300,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 266,700,000
Number of Reported Claims | Integer	950
Cumulative paid claims and allocated claim adjustment expense, Net	$ 65,500,000
Accident Year 2022 | Casualty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	248,700,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 179,100,000
Number of Reported Claims | Integer	478
Cumulative paid claims and allocated claim adjustment expense, Net	$ 9,400,000
Accident Year 2022 | Specialty Reinsurance
Claims Development [Line Items]
Incurred Claims and Allocated Claim Adjustment Expense, Net	193,900,000
Incurred but Not Reported (IBNR) Claims Liability, Net	$ 107,900,000
Number of Reported Claims | Integer	969
Cumulative paid claims and allocated claim adjustment expense, Net	$ 25,800,000

Reserves for Losses and Adjus_9

Reserves for Losses and Adjustment Expenses Short-duration insurance contracts - Reconciliation of Claims Development (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		$ 3,151.6		$ 4,484
Reinsurance recoverable on unpaid losses		4,897.7		3,298.1
Unallocated claims incurred		41.4		56.6
Carbon syndicate reserves		5.2		1
Other		1.6		0.2
Liability for unpaid claims and claim adjustment expense, aggregate reconciling items		(338.4)		(170.3)
Losses and loss adjustment expenses	$ 7,740.9	7,710.9	$ 7,511.8	7,611.8	$ 7,165.3	$ 6,951.8
Property Insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		259		289.3
Casualty Insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		457.3		725.6
Marine, Aviation and Energy Insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		163.7		427.9
Financial and Professional Insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		671.9		808.7
Insurance lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		1,551.9		2,251.5
Reinsurance recoverable on unpaid losses		2,907.8		2,117.4
Property Catastrophe and Other Property Reinsurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		677.9		784.9
Casualty Reinsurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		571.6		975.3
Specialty Reinsurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		350.2		472.3
Reinsurance lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liability for claims and claim adjustment expenses, net of reinsurance		1,599.7		2,232.5
Reinsurance recoverable on unpaid losses		1,989.9		1,180.7
Insurance lines other than short-duration
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Other reinsurance balances recoverable		(429.3)		(286.4)
Losses and loss adjustment expenses		$ 42.7		$ 58.3

Reserves for Losses and Adju_10

Reserves for Losses and Adjustment Expenses Short-duration Contracts - Historical Claims Duration (Details)	Dec. 31, 2022
Insurance
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year One	16.60%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Two	27%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Three	19.40%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Four	13.60%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Five	8.30%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Six	9.60%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Seven	6%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Eight	4.70%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Nine	2.20%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year Ten	2.60%
Reinsurance
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year One	20.50%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Two	33.70%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Three	15.70%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Four	10.10%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Five	7.80%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Six	5.90%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Seven	4.30%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Eight	2.70%
Average Annual Percentage Payout of Incurred Claims, Net of Reinsurance, Year Nine	2.30%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year Ten	1.90%

Income Taxes - Summary of Total

Income Taxes - Summary of Total Income Tax (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income tax (benefit)/expense allocated to net income	$ 36.2	$ 4.7	$ (78.1)	$ 5.3	$ 18.4
Income tax (benefit)/expense allocated to other comprehensive income			(23.9)	0.3	0.5
Total income tax (benefit)/expense			$ (102)	$ 5.6	$ 18.9

Income Taxes - Income_(Loss) Be

Income Taxes - Income/(Loss) Before Tax and Income Tax Expense/(Benefit) Attributable to that Income (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Examination [Line Items]
(Loss) before tax, Non-U.S.			$ (20.9)	$ (67.9)	$ 12.8
(Loss) before tax, U.S.			34.8	5	19.7
Income (loss) from operations before income taxes	$ 255.1	$ 53.1	(27)	35.1	(38)
Current tax (benefit)/expense, Non-U.S.			4.7	2.7	10.3
Current tax (benefit)/expense, U.S.			14.8	5.8	8.9
Current tax (benefit)/expense, Total			26.5	8.5	19.3
Deferred tax (benefit), Non-U.S.			(1.7)	(2.9)	(0.9)
Deferred tax (benefit), U.S.			(102.9)	0	0
Deferred tax, Total			(104.6)	(3.2)	(0.9)
Total tax expense/(benefit), Non-U.S.			3	(0.2)	9.4
Total tax expense/(benefit), U.S.			(88.1)	5.8	8.9
Total tax expense/(benefit)	$ 36.2	$ 4.7	(78.1)	5.3	18.4
Current tax expenses (benefit) related to prior year			14.8
Base erosion and anti-abuse (BEAT) expense			2.3	6.1	4.3
U.S. operating subsidiaries
Income Tax Examination [Line Items]
Base erosion and anti-abuse (BEAT) expense			1.1
Aspen U.K.
Income Tax Examination [Line Items]
Base erosion and anti-abuse (BEAT) expense			1.2
Bermuda
Income Tax Examination [Line Items]
(Loss) before tax, Non-U.S.			(103.3)	22.9	(81.5)
Current tax (benefit)/expense, Non-U.S.			0	0	0
Deferred tax (benefit), Non-U.S.			0	0	0
Total tax expense/(benefit), Non-U.S.			0	0	0
U.K.
Income Tax Examination [Line Items]
(Loss) before tax, Non-U.S.			62.4	75.1	11
Current tax (benefit)/expense, Non-U.S.			7	0	0.1
Deferred tax (benefit), Non-U.S.			0	(0.3)	0
Total tax expense/(benefit), Non-U.S.			$ 7	$ (0.3)	$ 0.1

Income Taxes - Income Tax Recon

Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
	Apr. 01, 2023	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax benefit at statutory tax rate of zero percent				$ 0	$ 0	$ 0
Overseas statutory tax rates differential				16.8	(0.9)	(3.8)
Base erosion and anti-abuse (BEAT) expense				2.3	6.1	4.3
Prior year adjustments				(2.9)	0.5	(25)
Change in valuation allowance (2)				(98.9)	9.6	40.8
Impact of unrecognized tax benefits				0	0	0
Australian non-resident withholding tax				1.5	0.6	1
Foreign exchange				(0.3)	(1.5)	0.2
Non-deductible expenses				2.4	2.4	4.7
Impact of changes in statutory tax rates (4)				(5.7)	(11.5)	(3.8)
Effective Income Tax Rate Reconciliation, Tax Effect of OCI, Amount				6.7	0	0
Total tax expense/(benefit)		$ 36.2	$ 4.7	(78.1)	$ 5.3	$ 18.4
U.S. operating subsidiaries
Operating Loss Carryforwards [Line Items]
Base erosion and anti-abuse (BEAT) expense				1.1
Aspen U.K.
Operating Loss Carryforwards [Line Items]
Base erosion and anti-abuse (BEAT) expense				$ 1.2
U.K.
Operating Loss Carryforwards [Line Items]
U. K. corporate tax rate				19%
U.K. | Forecast
Operating Loss Carryforwards [Line Items]
U. K. corporate tax rate	25%
Lloyd's syndicate
Operating Loss Carryforwards [Line Items]
Valuation allowance, associated losses				$ 0

Income Taxes - Tax Effects of D

Income Taxes - Tax Effects of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Operating loss carryforwards	$ 167.6	$ 170.2
Capital loss carryforwards	6.7	0.3
Insurance reserves: Losses and loss adjustment expenses	28.3	16.7
Unrealized losses on investments	20.6	0
Accrued expenses	6.1	4.6
Foreign tax credit carryforwards	19.8	20.2
Unearned premiums	36	28.3
Intangible assets	0.7	0
Office properties and equipment	14.2	15.1
Operating lease liability	18.5	19.2
Other temporary differences	3.7	2.9
Total deferred tax assets	322.2	277.5
Less valuation allowance	(145.7)	(225.9)
Deferred tax assets, net of valuation allowance	176.5	51.6
Unrealized (gains) on investments	0	(2.5)
Intangible assets	0	(2.8)
Deferred acquisition costs	(37)	(28.6)
Operating lease assets	(13.7)	(10.6)
Deferred Tax Liabilities, GAAP differences	0.2	8.3
Other temporary differences	(6.4)	(1.6)
Total deferred tax (liabilities)	(57.3)	(54.4)
Deferred tax assets, net	$ 119.2
Deferred tax liabilities, net		$ (2.8)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
United States corporate tax at a rate	21%
Capital loss carryforwards	$ 6.7	$ 0.3
Less valuation allowance	145.7	225.9
Deferred Tax Liabilities, Net		2.8
Deferred Tax Assets, Gross	322.2	277.5
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Capital loss carryforwards	31.7
Aspen U.K. | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Capital loss carryforwards	16.7
U.S. operating subsidiaries | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Capital loss carryforwards	15
Lloyd's | U.K.
Income Taxes [Line Items]
Deferred tax losses, operating loss carryforward	(19.9)	(66.2)
Other juridictions | U.K.
Income Taxes [Line Items]
Deferred tax losses, operating loss carryforward	(118.8)	(103.9)
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Net operating loss carryforwards	376.5	443.1
Operating loss carryforwards, remaining	376.5
Charitable contribution carryforwards	0	0.1
Less valuation allowance	18	119.7
Internal Revenue Service (IRS) | Aspen U.K.
Income Taxes [Line Items]
Net operating loss carryforwards	67.1
Operating loss carryforwards, subject to s382 limitation	6.5
Internal Revenue Service (IRS) | U.S. operating subsidiaries
Income Taxes [Line Items]
Net operating loss carryforwards	309.4
Operating loss carryforwards, subject to s382 limitation	$ 20.8
Internal Revenue Service (IRS) | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, date of expiration	2032
Internal Revenue Service (IRS) | Maximum
Income Taxes [Line Items]
Operating loss carryforwards, date of expiration	2041
U.K.
Income Taxes [Line Items]
U. K. corporate tax rate	19%
Net operating loss carryforwards	$ 280.5	168.9
Operating loss carryforwards, remaining	19.8	20.2
Less valuation allowance	$ 106.7	$ 88.7
Bermuda
Income Taxes [Line Items]
Bermuda tax rate	0%

Capital Structure - Summary of

Capital Structure - Summary of Authorized and Issued Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands				6 Months Ended	12 Months Ended
	Jun. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	May 02, 2013
Authorized share capital:
Number of ordinary shares				70,000,000	70,000,000	70,000,000
Number of preference shares				30,000,000	30,000,000	30,000,000
Ordinary Shares, authorized				$ 700	$ 700	$ 700
Preference Shares, authorized				45	45	45
Total authorized share capital				$ 745	$ 745	$ 745
Issued share capital:
Ordinary shares, issued				60,395,839	60,395,839	60,395,839
Ordinary shares, value				$ 604	$ 604	$ 604
Total issued share capital				$ 636	$ 636	$ 636
Ordinary shares, par value				$ 0.01	$ 0.01	$ 0.01
Preference shares, par value				$ 0.0015144558	$ 0.0015144558
5.950% Preference Shares (AHL PRC)
Issued share capital:
Preference shares, issued				11,000,000	11,000,000	11,000,000	11,000,000
Preference shares, value				$ 17	$ 17	$ 17
Preferred Stock, Dividend Rate, Percentage	5.95%			5.95%	5.95%	5.95%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share							$ 25
5.625% Preference Shares (AHL PRD)
Issued share capital:
Preference shares, issued			10,000,000	10,000,000	10,000,000	10,000,000
Preference shares, value				$ 15	$ 15	$ 15
Preferred Stock, Dividend Rate, Percentage	5.625%		5.625%	5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share			$ 25	$ 25	$ 25	$ 25
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Issued share capital:
Preference shares, issued		10,000,000		10,000,000	10,000,000	10,000,000
Preference shares, value				$ 0	$ 0	$ 0
Preferred Stock, Dividend Rate, Percentage	5.625%	5.625%		5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share		$ 25		$ 25	$ 25	$ 25

Capital Structure - Summary o_2

Capital Structure - Summary of Authorized and Issued Share Capital (Details)(Phantom) - $ / shares	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 13, 2019	Sep. 20, 2016	May 02, 2013
Class of Stock [Line Items]
Ordinary shares, par value	$ 0.01	$ 0.01	$ 0.01
Preference shares, par value	0.0015144558	0.0015144558
5.950% Preference Shares (AHL PRC)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share						$ 25
5.625% Preference Shares (AHL PRD)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share	25	25	25		$ 25
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share	$ 25	$ 25	$ 25	$ 25

Capital Structure - Additional

Capital Structure - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					6 Months Ended	12 Months Ended
	Jun. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	May 02, 2013	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Additional paid in capital						$ 1,514,700	$ 1,514,700
Aggregate liquidation preferences					$ 775,000	775,000	775,000
Preferred stock issuance cost					21,500	21,500	21,500
Authorized share capital					$ 745	$ 745	$ 745
Number of ordinary shares					70,000,000	70,000,000	70,000,000
Ordinary shares, par value					$ 0.01	$ 0.01	$ 0.01
Number of preference shares					30,000,000	30,000,000	30,000,000
Preference shares, par value					$ 0.0015144558	$ 0.0015144558
Ordinary shares, issued					60,395,839	60,395,839	60,395,839
Preference shares liquidation preference, value		$ 250,000
Capital contribution						$ 0	$ 45,000	$ 268,000
5.950% Preference Shares (AHL PRC)
Class of Stock [Line Items]
Preferred stock issuance cost				$ 4,400
Preference shares, par value					$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued				11,000,000	11,000,000	11,000,000	11,000,000
Preference shares, rate	5.95%				5.95%	5.95%	5.95%
Redemption price per share				$ 25
Proceeds or share issuance				$ 270,600
Preference shares liquidation preference, value				$ 275,000
5.625% Preference Shares (AHL PRD)
Class of Stock [Line Items]
Preferred stock issuance cost			$ 8,700						$ 8,700
Preference shares, par value					$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued			10,000,000		10,000,000	10,000,000	10,000,000
Preference shares, rate	5.625%		5.625%		5.625%	5.625%	5.625%
Redemption price per share			$ 25		$ 25	$ 25	$ 25
Proceeds or share issuance			$ 241,300
Preference shares liquidation preference, value			$ 250,000						$ 250,000
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Class of Stock [Line Items]
Preferred stock issuance cost		$ 8,400
Preference shares, par value					$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued		10,000,000			10,000,000	10,000,000	10,000,000
Preference shares, rate	5.625%	5.625%			5.625%	5.625%	5.625%
Redemption price per share		$ 25			$ 25	$ 25	$ 25
Additional paid-in capital | Preference shares
Class of Stock [Line Items]
Proceeds or share issuance		$ 241,600

Statutory Requirements and Di_2

Statutory Requirements and Dividends Restrictions - Summary of Statutory Requirements and Dividends Restrictions (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
U.S.
Required statutory capital and surplus	$ 513.9	$ 561.2
Actual statutory capital and surplus	838.6	889.7
Bermuda
Required statutory capital and surplus	536.7	683.7
Actual statutory capital and surplus	1,426.5	1,141
U.K.
Required statutory capital and surplus	771.8	800.7
Actual statutory capital and surplus	$ 802.5	$ 963.6

Statutory Requirements and Di_3

Statutory Requirements and Dividends Restrictions - Additional Information (Details) - 12 months ended Dec. 31, 2022 £ in Millions, $ in Millions	USD ($)	GBP (£)
AUL
Statutory Accounting Practices [Line Items]
Syndicate to maintain funds at Lloyd	$ 968.7
Total funds held by AUL	1,045.9
U.K.
Statutory Accounting Practices [Line Items]
Dividend payment made without regulatory approval	(467.4)	£ (62.2)
Capital contributions reserves	655
Bermuda
Statutory Accounting Practices [Line Items]
Dividend payment made without regulatory approval	$ (262.1)
Statutory capital and surplus, percent	25%
Statutory capital and surplus, percent reduction requiring approval	15%
Percent warning level of amount of enhanced capital required from statutory capital and surplus	120%
Bermuda | AUL
Statutory Accounting Practices [Line Items]
Total funds held by AUL	$ 479.6

Dividends - Summary of Declared

Dividends - Summary of Declared Dividends (Details) - USD ($) $ / shares in Units, $ in Millions								6 Months Ended	12 Months Ended
	Jul. 01, 2023	Jun. 15, 2023	Apr. 14, 2023	Apr. 01, 2023	Mar. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 01, 2023
Dividends Payable [Line Items]
Payments of Ordinary Dividends								$ 20	$ 40
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.625%				5.625%		5.625%	5.625%	5.625%
5.950% Preference Shares (AHL PRC)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.95%						5.95%	5.95%	5.95%
5.625% Preference Shares (AHL PRD)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.625%					5.625%	5.625%	5.625%	5.625%
Subsequent Event
Dividends Payable [Line Items]
Payments of Ordinary Dividends			$ 20
Subsequent Event | 5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 351.56										$ 351.56
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Depositary share dividend	$ 0.35156										0.35156
Preferred Stock, Dividend Rate, Percentage					5.625%
Subsequent Event | 5.950% Preference Shares (AHL PRC)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 0.3719										0.3719
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Preferred Stock, Dividend Rate, Percentage					5.95%
Subsequent Event | 5.625% Preference Shares (AHL PRD)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 0.3516										$ 0.3516
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Preferred Stock, Dividend Rate, Percentage					5.625%

Retirement Plans (Details)

Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Total contributions by the Company to the retirement plan	$ 12.5	$ 13.5	$ 12.1

Share-Based Payments and Long_2

Share-Based Payments and Long-term Incentive Plan - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment and LTIP expense	$ 0.6	$ 0.5
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 0.6	$ 0.5

Intangible Assets - Summary of

Intangible Assets - Summary of Changes in Intangible Assets (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 18, 2017	Dec. 31, 2022	Dec. 31, 2021
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Amortization		$ (0.1)	$ (0.9)
Goodwill [Roll Forward]
Goodwill, Beginning of the period		3.9	3.9
Goodwill, Additions (Disposals)		0	0
Goodwill, Impairment Loss		0	0
Goodwill, End of the Period		3.9	3.9
Intangible Assets and goodwill, Beginning of the period		21.9	22.8
Intangible Assets and Goodwill, Additions (Disposals)		0	0
Goodwill and Intangible Asset Impairment		0	0
Intangible Assets and goodwill, End of the period		21.8	21.9
Trademarks
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		1.3	1.6
Intangible Assets acquired (disposed)	$ 0		0
Amortization		(0.1)	(0.3)
Impairment of intangible assets (excluding goodwill)		0	0
Intangible Assets, End of the period		1.2	1.3
Agency Relationships
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		0	0.6
Intangible Assets acquired (disposed)			0
Amortization			(0.6)
Impairment of intangible assets (excluding goodwill)			0
Intangible Assets, End of the period			0
Insurance Licenses
Finite and Indefinite Lived Intangible Assets [Roll Forward]
Intangible Assets, Beginning of the period		16.7	16.7
Intangible Assets acquired (disposed)		0	0
Amortization		0	0
Impairment of intangible assets (excluding goodwill)		0	0
Intangible Assets, End of the period		$ 16.7	$ 16.7

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	Jan. 01, 2017	Oct. 31, 2016	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2010
Blue Waters
Finite-Lived Intangible Assets [Line Items]
Goodwill, acquired		$ 2.1
Trademarks
Finite-Lived Intangible Assets [Line Items]
Value of the asset			$ 1.2	$ 1.3	$ 1.6
Aspen trademark
Finite-Lived Intangible Assets [Line Items]
Value of the asset			1.2
Insurance Licenses
Finite-Lived Intangible Assets [Line Items]
Value of the asset			16.7	$ 16.7	$ 16.7	$ 10
Insurance Licenses | Aspen Specialty
Finite-Lived Intangible Assets [Line Items]
Value of the asset			4.5
Insurance Licenses | Aspen U.K.
Finite-Lived Intangible Assets [Line Items]
Value of the asset			$ 2.1
Digital Re
Finite-Lived Intangible Assets [Line Items]
Goodwill, acquired	$ 1.8
Equity method investment, ownership percentage	49%

Operating Leases - Schedule of

Operating Leases - Schedule of Operating Lease Costs (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Amortization of right-of-use operating lease assets	$ 5.1	$ 5.2	$ 10.1	$ 12	$ 11.8
Interest on operating lease liability			5.4	5.5
Operating lease charge			$ 15.5	$ 17.5	$ 17.3

Operating Leases - Schedule o_2

Operating Leases - Schedule of Operating Lease Liability, Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Liability, Payments, Due prior year		$ 0	$ 17
Liability, Payments, Next twelve months		15.4	17
Liability, Payments, Due year two		15.2	16.5
Liability, Payments, Due year three		14.9	16.1
Liability, Payments, Due year four		14.1	15.3
Liability, Payments, Due year five		12.6	13.8
Liability, Payments, Due after year five		47.2	48
Total minimum lease payments		119.4	143.7
Less imputed interest		(23.9)	(28.5)
Operating lease liabilities	$ 91.3	$ 95.5	$ 115.2

Operating Leases - Schedule o_3

Operating Leases - Schedule of Operating Leases Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease liabilities	$ (15.5)	$ (17.5)	$ (17.3)
Asset obtained in exchange for operating lease liability	1.9	23.9
Reduction of right-of use assets resulting from reductions to lease obligations	$ 7	$ 2.3
Operating lease, weighted average remaining lease term (years(	8 years 1 month 6 days	8 years 9 months 18 days
Operating lease, weighted average discount rate (percent)	5%	5%

Operating Leases - Additional I

Operating Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2023
Leases [Abstract]
Right-of-use operating lease assets	$ 72.8	$ 83.4
Operating lease liabilities	95.5	115.2		$ 91.3
Non-operating expenses related to impairment charges on lease assets	$ (6.7)	$ (0.4)	$ (12.9)

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Related Party Transaction [Line Items]
Plus component of annual investment management fee	0.25	0.25
Annual fee cap	0.15	0.15
Privately-held Investments	$ 482.4	$ 533		$ 307.1
Other investments, at fair value (2)	213.4	221.3		151.3
Asset Management Arrangement
Related Party Transaction [Line Items]
Related party fees				5.8	$ 5.3
Asset Management Arrangement | Investment Income
Related Party Transaction [Line Items]
Related party fees	5.2	4.9	$ 0.6
Management Consulting Agreement
Related Party Transaction [Line Items]
Related party fees				5	$ 5
Management Consulting Agreement | General, administrative and corporate expenses
Related Party Transaction [Line Items]
Related party fees	2.5	5	2.5
Apollo originating partnership | Gain (Loss) on Investments
Related Party Transaction [Line Items]
Related party fees	0.4	1.5	0.2
Beneficial owner
Related Party Transaction [Line Items]
Intercompany balance payable	2.2	2		0.6
Apollo real estate fund | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Other investments, at fair value (2)	22.9	25.3
Apollo originating partnership | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	42.7	44.8
Other investments, at fair value (2)	12.6	12.7
Apollo originating partnership, class A notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred	(1.3)	(0.2)	(0.5)
Apollo originating partnership, class A notes | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	28.6	30
Apollo originating partnership, class B notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred	(0.7)	(0.2)	$ (0.3)
Apollo originating partnership, class B notes | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	$ 14	$ 14.8
Apollo, Class A & B Notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred				$ 0
Maximum
Related Party Transaction [Line Items]
Percentage of consolidated group's net income due to Apollo Management	1%	1%
Fees due to Apollo Management	$ 5	$ 5

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Company's Restricted Assets (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 01, 2022	Sep. 30, 2021	Dec. 20, 2017
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	$ 266.5	$ 471.3	$ 539.8
Restricted assets, excluding illiquid assets	3,657.3	3,996.1	4,530.8
Other investments, at fair value (2)	213.4	221.3	151.3
Total restricted assets	$ 3,870.7	$ 4,217.4	$ 4,682.1
Total as percent of investable assets	52.60%	59.40%	59.70%
Securities and cash as collateral secured letters of credit	$ 266.5	$ 471.3	$ 539.8
Affiliated transactions
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	617	707.1	891.3
Third party
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	2,773.8	2,817.7	3,099.7
Limited Partner | Real estate fund
Fair Value, Separate Account Investment [Line Items]
Restricted Assets				$ 10	$ 20	$ 100
Other investments, at fair value (2)	$ 213.4	$ 221.3	$ 151.3

Commitments and Contingencies_4

Commitments and Contingencies - Additional Information (Details) £ in Millions, SFr in Millions, $ in Millions, $ in Millions, $ in Millions, $ in Millions	1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) Investment	Dec. 31, 2021 USD ($) Investment	Dec. 31, 2020 USD ($)	Jun. 30, 2023 GBP (£)	Jun. 30, 2023 CAD ($)	Jun. 30, 2023 AUD ($)	Jun. 30, 2023 CHF (SFr)	Jun. 30, 2023 SGD ($)	Dec. 31, 2022 GBP (£) Investment	Dec. 31, 2022 CAD ($) Investment	Dec. 31, 2022 AUD ($) Investment	Dec. 31, 2022 CHF (SFr) Investment	Dec. 31, 2022 SGD ($) Investment	Apr. 01, 2022 USD ($)	Dec. 31, 2021 GBP (£) Investment	Dec. 31, 2021 CAD ($) Investment	Dec. 31, 2021 AUD ($) Investment	Dec. 31, 2021 CHF (SFr) Investment	Dec. 31, 2021 SGD ($) Investment	Sep. 30, 2021 USD ($)	Dec. 23, 2019 USD ($)	Dec. 20, 2017 USD ($)
Restricted Cash And Collateral [Line Items]
Restricted assets		$ 266.5		$ 471.3	$ 539.8
Other investments (equity method)		$ 213.4		$ 221.3	$ 151.3
Total as percent of investable assets		52.60%		59.40%	59.70%
Investment in the period		$ 0.4		$ 2	$ 3.2
Commitment to invest in private assets		23.1	$ 175.6	377.9	205.1	$ 92.8
Investable assets held by the Company		7,400		7,100	7,800
Investable assets held by insurance regulators		$ 551		$ 489.5	565.8
Minimum capital required | £							£ 0.4					£ 0.4						£ 0.4
Percentage of reinsurance liabilities		100%		100%			100%	100%	100%	100%	100%	100%	100%	100%	100%	100%
Reinsurance liabilities		$ 1,009.3		$ 1,166.4	1,470.5
Assets held-in-trust		1,167.8		1,389.5	1,581.9
Regulatory deposits		10.3		6.7	6.9
Deposit with states		6.7		$ 6.5	$ 6.4
Number of investments | Investment				1	1							1	1	1	1	1		1	1	1	1	1
MVI
Restricted Cash And Collateral [Line Items]
Investment in the period	$ 0.8	0		$ 0.4	$ 0.4
Multi-Line Insurer
Restricted Cash And Collateral [Line Items]
Other investments (equity method)																								$ 5
Investment in the period		0.4		1.6	2.5
Us Multi Beneficiary Trust Fund
Restricted Cash And Collateral [Line Items]
Minimum trust fund		20		20
Assets held-in-trust		383.2		509.2	519.7
Us Surplus Lines Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		141		215.1	216
Canadian Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		151.8		137.2				$ 200.9					$ 185.8						$ 196.8
Australian Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		102		124.7					$ 153.2					$ 183.9						$ 226.6
Swiss Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		10.6		10.2						SFr 9.5					SFr 9.4						SFr 8
Singapore Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		$ 127.5		$ 130.3							$ 172.6					$ 174.7						$ 178
Bermuda
Restricted Cash And Collateral [Line Items]
Percentage of reinsurance liabilities		100%		100%			100%	100%	100%	100%	100%	100%	100%	100%	100%	100%
Reinsurance liabilities		$ 306.7		$ 380.3	450.4
Limited Partner | Real estate fund
Restricted Cash And Collateral [Line Items]
Restricted assets																	$ 10						$ 20		$ 100
Other investments (equity method)		$ 213.4		$ 221.3	$ 151.3

Concentration of Credit Risk -

Concentration of Credit Risk - Schedule Of Gross Written Premium From Major Brokers (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Gross written premiums, percentage			100%	100%	100%
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Percentage of written premium major broker accounted minimum			10%
Aon Corporation
Investment Holdings [Line Items]
Gross written premiums, percentage			22.30%	17.30%	15.80%
Marsh & McLennan Companies, Inc.
Investment Holdings [Line Items]
Gross written premiums, percentage			21.80%	17.50%	15.40%
Willis Group Holdings, Ltd.
Investment Holdings [Line Items]
Gross written premiums, percentage			8%	9.60%	10.40%
Others
Investment Holdings [Line Items]
Gross written premiums, percentage			47.90%	55.60%	58.40%

Concentration of Credit Risk _2

Concentration of Credit Risk - Additional Information (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2020 USD ($)
Concentration Risk [Line Items]
Less foreign exchange (gains)/losses	$ 4,658	$ 4,897.7	$ 3,298.1	$ 5,006.5	$ 3,195.2
Reinsurance Recoverables, Uncollateralized		2,092.4	1,981.4
Underwriting premiums receivables (net of allowance for expected credit losses of 2022: $25.0 — 2021: $30.2)	1,676.8	1,482.4	1,304.6
Due for settlement	5.9	18.3
Premium Receivable, Allowance for Credit Loss	$ 21.6	$ 25	30.2
Allowable holdings of a single issue or issuer, percentage	2%	2%
Percentage of written premium major broker accounted minimum		10%
Reinsurance Recoverable, Allowance for Credit Loss	$ 3.3	$ 3.7	$ 3.3		$ 3.8
Munich Re
Concentration Risk [Line Items]
Concentration risk	0.092	0.097
Everest Re
Concentration Risk [Line Items]
Concentration risk	0.160	0.163
Lloyd's
Concentration Risk [Line Items]
Concentration risk	0.078	0.082
AM Best, A plus Rating | Standard & Poor's, A plus Rating | Everest Re
Concentration Risk [Line Items]
Concentration risk		0.163	0.159
AM Best, A plus Rating | Standard & Poor's, AA- Rating | Munich Re
Concentration Risk [Line Items]
Concentration risk		0.097	0.108
AM Best, A Rating | Standard & Poor's, A plus Rating | Lloyd's
Concentration Risk [Line Items]
Concentration risk		0.082	0.093

Reclassifications from Accumu_5

Reclassifications from Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income Reclassification (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from operations before income taxes	$ 255.1	$ 53.1	$ (27)	$ 35.1	$ (38)
Income tax (expense)/benefit	(36.2)	(4.7)	78.1	(5.3)	(18.4)
General, administrative and corporate expenses	(232.7)	(233.4)	(494.2)	(418)	(410.9)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Net (loss)	218.9	48.4	51.1	29.8	$ (56.4)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income/(loss)	2.5	22	70.4	(26.6)
Available for sale securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Available for sale securities — gross realized (losses)	(0.4)	(2.3)	(3.9)	(24.8)
Realized losses on sale of securities and cash and cash equivalents	7.2	30.1	58.9	4.4
Income (loss) from operations before income taxes	6.8	27.8	55	(20.4)
Income tax (expense)/benefit	0	0	0	0
Net (loss)	6.8	27.8	55	(20.4)
Realized derivatives | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax (expense)/benefit	0	0.6	0	0
General, administrative and corporate expenses	(4.3)	(6.4)	15.4	(6.2)
Net income/(loss)	$ (4.3)	$ (5.8)	$ 15.4	$ (6.2)

Credit Facilities and Short-T_2

Credit Facilities and Short-Term Debt - Summary of Contractual Obligations Under Short-term Debts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Jun. 30, 2023	Dec. 31, 2021
Line of Credit Facility [Line Items]
Short-term debt	$ 299.9	$ 299.9	$ 0
Total	300
Short-Term Debt
Line of Credit Facility [Line Items]
Short-term debt	$ 300

Credit Facilities and Short-T_3

Credit Facilities and Short-Term Debt - Additional Information (Details) - USD ($)

12 Months Ended

Dec. 01, 2021

Nov. 13, 2013

Dec. 31, 2022

Dec. 31, 2021

Feb. 07, 2023

Oct. 27, 2022

Jun. 17, 2022

Dec. 29, 2021

Nov. 30, 2021

Nov. 05, 2021

Apr. 01, 2021

Nov. 30, 2020

Nov. 03, 2020

Feb. 11, 2019

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 300,000,000

Line of credit facility Increasable capacity

$ 100,000,000

Minimum consolidated tangible net worth under credit facility

$ 2,019,600,000

Percentage of consolidated net income

25%

Percentage of aggregate net cash proceeds from the issuance of capital stock

25%

Percentage of consolidated leverage ratio permitted

35%

Securities lending transaction

$ 50,000,000

Maximum

Line of Credit Facility [Line Items]

Securities lending transaction

$ 50,000,000

Aspen U.K. | Deutsche

Line of Credit Facility [Line Items]

Line of Credit Facility, Commitment Fee Amount

22,800,000

Aspen U.K. | Citibank Europe

Line of Credit Facility [Line Items]

Line of Credit Facility, Commitment Fee Amount

75,100,000

AUL | Lloyd's

Line of Credit Facility [Line Items]

Letter of Credit to Support Funds at Lloyd's

$ 285,000,000

Funds at Lloyd's Facility Agreement

$ 80,000,000

$ 150,000,000

AUL | Lloyd's | Maximum

Line of Credit Facility [Line Items]

Letter of Credit to Support Funds at Lloyd's

$ 235,000,000

Bermuda | Natixis

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 100,000,000

Bermuda | HSBC Bank USA, National Association

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 75,000,000

Aspen Specialty | Federal Home Loan Bank of Boston

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 223,000,000

Percentage limit of pledged assets permitted to secure debt obligations

15%

AAIC | Federal Home Loan Bank of Boston

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 141,000,000

Percentage limit of pledged assets permitted to secure debt obligations

10%

Citibank Europe

Line of Credit Facility [Line Items]

Outstanding collateralized letters of credit facility

416,800,000

$ 452,400,000

Letters of credit / guarantees | Aspen U.K. | Aspen European

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 100,000,000

Letters of credit / guarantees | Aspen U.K. | Aspen European | Subsequent Event

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

$ 100,000,000

Standby Letters of Credit | Bermuda

Line of Credit Facility [Line Items]

Line of Credit Facility, Commitment Fee Amount

100,000,000

Standby Letters of Credit | Bermuda | Deutsche

Line of Credit Facility [Line Items]

Line of Credit Facility, Commitment Fee Amount

120,000,000

Citibank Europe plc | Letters of credit / guarantees

Line of Credit Facility [Line Items]

Revolving credit facility, credit agreement maximum limit

400,000,000

Senior Notes

Line of Credit Facility [Line Items]

Loans issued

$ 300,000,000

Debt stated interest rate

4.65%

Net proceeds from senior notes

$ 299,700,000

Amount of indebtedness subject to default in payment

50,000,000

Annual interest payable

$ 14,300,000

Credit Losses (Details)

Credit Losses (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Credit Loss [Abstract]
Reinsurance Recoverable, Allowance for Credit Loss, Beginning Balance	$ 3.7	$ 3.3	$ 3.8
Reinsurance Recoverable, Allowance for Credit Loss, Period Increase (Decrease)	(0.4)	0.4	(0.5)
Reinsurance Recoverable, Allowance for Credit Loss, Ending Balance	3.3	3.7	3.3
Accounts Receivable, Allowance for Credit Loss, Beginning Balance	25	30.2	34
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		(5.2)	(3.8)
Accounts Receivable, Allowance for Credit Loss, Ending Balance		25	30.2
Available-for-sale Investments, Allowance for Credit Loss, Beginning Balance	7.7	2.7	0.2
Available-for-sale investment, allowance for credit loss, increase (decrease)	(3.7)	5	2.5
Available-for-sale Investments, Allowance for Credit Loss, Current	4	7.7	2.7
Total, Allowance for Credit Loss, Beginning Balance	$ 36.4	36.2	38
Total allowance for credit losses increase (decrease)		0.2	(1.8)
Total, Allowance for Credit Loss, Ending Balance		$ 36.4	$ 36.2

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Apr. 14, 2023	Jun. 30, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Payments of Ordinary Dividends		$ 20	$ 40
Subsequent Event
Subsequent Event [Line Items]
Payments of Ordinary Dividends	$ 20

Schedule II - Condensed Finan_2

Schedule II - Condensed Financial Information of Registrant Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands				6 Months Ended	12 Months Ended
	Jun. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	Dec. 31, 2020	Dec. 31, 2019	May 02, 2013
ASSETS
Cash and cash equivalents (including cash within consolidated variable interest entities of — $65.7448377 and $75.15054353)				$ 1,061,500	$ 959,200	$ 1,314,100
Other investments (equity method)				213,400	221,300	151,300
Right-of-use operating lease assets					72,800	83,400
Other assets					7,400	8,300
Total assets				15,393,100	15,157,300	13,844,100
LIABILITIES
Accrued expenses and other payables (4)				171,400	201,800	289,300
Short-term debt				299,900	299,900	0
Long-term debt					0	299,900
Operating lease liabilities				91,300	95,500	115,200
Total liabilities				12,844,400	12,799,300	11,069,300
SHAREHOLDERS’ EQUITY
60,395,839 ordinary shares of par value $0.01 each (December 31, 2021 — 60,395,839 shares)				604	604	604
Additional paid in capital					1,514,700	1,514,700
Retained earnings				1,525,700	1,349,000	1,382,500
Total accumulated other comprehensive (loss)				(492,300)	(506,300)	(123,000)	$ (435,000)	$ 19,700
Total liabilities and shareholders’ equity				$ 15,393,100	$ 15,157,300	$ 13,844,100
Ordinary shares, issued				60,395,839	60,395,839	60,395,839
Ordinary shares, par value				$ 0.01	$ 0.01	$ 0.01
Preference shares, par value				$ 0.0015144558	$ 0.0015144558
5.950% Preference Shares (AHL PRC)
SHAREHOLDERS’ EQUITY
Preference shares, issued				11,000,000	11,000,000	11,000,000				11,000,000
Preference shares, rate	5.95%			5.95%	5.95%	5.95%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
5.625% Preference Shares (AHL PRD)
SHAREHOLDERS’ EQUITY
Preference shares, issued			10,000,000	10,000,000	10,000,000	10,000,000
Preference shares, rate	5.625%		5.625%	5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
5.625% Preference Shares (AHL PRE)
SHAREHOLDERS’ EQUITY
Preference shares, issued		10,000,000		10,000,000	10,000,000	10,000,000
Preference shares, rate	5.625%	5.625%		5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Parent Company
ASSETS
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)					$ 40,500	$ 42,600
Cash and cash equivalents (including cash within consolidated variable interest entities of — $65.7448377 and $75.15054353)					44,400	45,000		$ 92,400	$ 37,400
Investments in subsidiaries (1)					2,767,900	3,142,000
Intercompany funds due from affiliates					1,700	1,300
Right-of-use operating lease assets					2,000	2,500
Other assets					5,900	8,000
Total assets					2,862,400	3,241,400
LIABILITIES
Accrued expenses and other payables (4)					22,300	25,500
Intercompany funds due to affiliates					180,500	139,000
Short-term debt					299,900	0
Long-term debt					0	299,900
Operating lease liabilities					1,700	2,200
Total liabilities					504,400	466,600
SHAREHOLDERS’ EQUITY
60,395,839 ordinary shares of par value $0.01 each (December 31, 2021 — 60,395,839 shares)					600	600
Additional paid in capital					1,514,700	1,514,700
Retained earnings					1,349,000	1,382,500
Unrealized (loss)/gains on investments					(333,200)	34,600
(Loss)/gain on derivatives					13,800	(1,600)
Gains on foreign currency translation (start of period)				$ (186,900)	(156,000)
Gains on foreign currency translation (end of period)					(186,900)	(156,000)
Total accumulated other comprehensive (loss)					(506,300)	(123,000)
Total shareholders’ equity					2,358,000	2,774,800
Total liabilities and shareholders’ equity					$ 2,862,400	$ 3,241,400
Ordinary shares, issued					60,395,839	60,395,839
Ordinary shares, par value					$ 0.0001	$ 0.0001

Schedule II - Condensed Finan_3

Schedule II - Condensed Financial Information of Registrant Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Dividend income	$ 134.7	$ 93.5	$ 198.4	$ 159.2	$ 167.3
Other income			8.2	14.7	49.8
Total revenues	1,452.9	1,418.4	2,890	2,628.9	2,830.4
Expenses
General, administrative and corporate expenses	(232.7)	(233.4)	(494.2)	(418)	(410.9)
Other expenses			(20.1)	(10.8)	(10.8)
Income (loss) from operations before income taxes	255.1	53.1	(27)	35.1	(38)
Income tax benefit/(expense)	(36.2)	(4.7)	78.1	(5.3)	(18.4)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Net (loss)/income attributable to Aspen Insurance Holdings Limited’s ordinary shareholders	196.7	26.2
Other Comprehensive Income:
Change in unrealized (losses)/gains on investments	10.7	(286.5)	(367.8)	(157.9)	108
Change in foreign currency translation adjustment	0	0.6
Other comprehensive (loss)/income, net of tax	14	(312)	(383.3)	(142.7)	96.4
Total comprehensive (loss)/income attributable to Aspen Insurance Holdings Limited's ordinary shareholders	$ 210.7	$ (285.8)	(332.2)	(112.9)	40
Parent Company
Condensed Financial Statements, Captions [Line Items]
Equity in net earnings/(losses) of subsidiaries and other investments, equity method			14.2	(90.5)	(108.4)
Dividend income			121.7	193	141.5
Net realized and unrealized investment (losses)/gains			(4)	(0.5)	2.5
Other income			1	0	0
Total revenues			132.9	102	35.6
Expenses
General, administrative and corporate expenses			(62.7)	(54.6)	(74.6)
Interest expense			(14.3)	(14.3)	(14.3)
Other expenses			(4.8)	(3.3)	(3.1)
Income (loss) from operations before income taxes			51.1	29.8	(56.4)
Income tax benefit/(expense)			0	0	0
Net income/(loss)			51.1	29.8	(56.4)
Proportion due to non-controlling interest			0	0	0
Net (loss)/income attributable to Aspen Insurance Holdings Limited’s ordinary shareholders			51.1	29.8	(56.4)
Other Comprehensive Income:
Change in unrealized (losses)/gains on investments			(367.8)	(158.6)	108
Net change from current period hedged transactions			15.4	(6.2)	0.3
Change in foreign currency translation adjustment			(30.9)	21.4	(11.9)
Other comprehensive (loss)/income, net of tax			(383.3)	(143.4)	96.4
Total comprehensive (loss)/income attributable to Aspen Insurance Holdings Limited's ordinary shareholders			$ (332.2)	$ (113.6)	$ 40

Schedule II - Condensed Finan_4

Schedule II - Condensed Financial Information of Registrant Statements of Cash Flows (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows (used in)/from operating activities:
Amortization of right-of-use operating lease assets		$ 5.1	$ 5.2	$ 10.1	$ 12	$ 11.8
Interest on operating lease liability				(5.4)	(5.5)
Change in right of lease assets				(6.7)	0.4	12.9
Change in operating lease liabilities				(15.5)	(17.5)	(17.3)
Net cash (used in)/from operating activities		264.6	104.8	(55)	524.7	(672.7)
Cash flows (used in)/from investing activities:
Proceeds/(purchases) of short term investments		(15)	0	(7)	(26.8)	(58.3)
Payments for acquisitions and investments, net of cash acquired		(0.4)		(2)	(3.2)
(Purchases) of other investments		(3)	(46.6)	(62.5)	(20)	0
Net cash (used in)/from investing activities		(124.5)	(92.9)	(196.5)	(950.3)	1,151.2
Cash flows used in/from financing activities:
Net cash (used in)/from financing activities		(42.2)	(42.2)	(84.6)	0.5	223.5
Cash and cash equivalents at beginning of period		959.2	1,314.1	1,314.1
Cash and cash equivalents at end of period (1)		1,061.5		959.2	1,314.1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		102.3	(49.2)	(354.9)	(433.2)	716.8
Proceeds from sales and maturities of fixed income securities — Trading		283.9	134.8	293.6	548.2	554.4
Parent Company
Cash flows (used in)/from operating activities:
Net income (excluding equity in net earnings of subsidiaries)				36.9	120.3	52
Realized and unrealized losses/(gains)				19.7	(6.7)	1.5
(Gain)/loss on derivative contracts				(15.4)	6.2	(0.3)
Amortization of right-of-use operating lease assets				0.5	0.5	0.4
Interest on operating lease liability				0.1	0.1	(0.4)
Change in other assets				2.1	(1.6)	0.5
Change in right of lease assets				0	(2)	0
Change in accrued expenses and other payables				(3.2)	1.4	15.9
Change in intercompany activities				41.1	35	41.6
Change in operating lease liabilities				(0.6)	1.5	0
Net cash (used in)/from operating activities				81.2	154.7	111.2
Cash flows (used in)/from investing activities:
(Purchases) of fixed income securities				(10)	(42.6)	75.6
Investment in subsidiaries				5	(115)	(87.3)
Net cash (used in)/from investing activities				2.8	(157.6)	(11.7)
Cash flows used in/from financing activities:
Net cash (used in)/from financing activities				(84.6)	(44.5)	(44.5)
Cash and cash equivalents at beginning of period		44.4	$ 45	45	92.4	37.4
Cash and cash equivalents at end of period (1)				44.4	45	92.4
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect				(0.6)	(47.4)	55
Proceeds from sales and maturities of fixed income securities — Trading				7.8	0	$ 0
MVI
Cash flows (used in)/from investing activities:
Payments for acquisitions and investments, net of cash acquired	$ (0.8)	$ 0		$ (0.4)	$ (0.4)

Schedule III - Supplementary _2

Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Policy Acquisition Costs			$ 319	$ 290.8	$ 306.6
Net Reserves for Losses and LAE	$ 3,082.9	$ 2,505.3	2,813.2	4,313.7	3,970.1	$ 4,632
Net Reserves for Unearned Premiums			1,720.2	1,516.2	1,363.7
Net earned premiums	1,287.4	1,327.2	2,688.7	2,410.5	2,527.5
Net Investment Income			188.1	147.5	154.6
Losses and LAE Expenses			1,680	1,693.3	1,840.8
Policy Acquisition Expenses			431.8	414.1	465.7
Net written premiums	$ 1,350.5	$ 1,506.1	2,896	2,587.7	2,577.8
General and Administrative Expenses			386.5	333.1	308
Reinsurance
Deferred Policy Acquisition Costs			227.2	205.2	206.8
Net Reserves for Losses and LAE			1,360.7	2,148.4	2,095.7
Net Reserves for Unearned Premiums			862.4	688.6	617.6
Net earned premiums			1,251.8	1,118.8	1,287.7
Losses and LAE Expenses			770.3	705.2	958.6
Policy Acquisition Expenses			252.4	221.6	246
Net written premiums			1,426.4	1,199	1,297.7
General and Administrative Expenses			142.5	121.3	110.8
Insurance
Deferred Policy Acquisition Costs			91.8	85.6	99.8
Net Reserves for Losses and LAE			1,452.5	2,165.3	1,874.4
Net Reserves for Unearned Premiums			857.8	827.6	746.1
Net earned premiums			1,436.9	1,291.7	1,239.8
Losses and LAE Expenses			909.7	988.1	882.2
Policy Acquisition Expenses			179.4	192.5	219.7
Net written premiums			1,469.6	1,388.7	1,280.1
General and Administrative Expenses			$ 244	$ 211.8	$ 197.2

Schedule IV - Reinsurance Premi

Schedule IV - Reinsurance Premiums Written and Premiums Earned (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Direct	$ 1,249.5	$ 1,305.7	$ 2,531.7	$ 2,341.4	$ 2,042.1
Assumed	875.7	1,045.6	1,807	1,597	1,656.4
Ceded	(774.7)	(845.2)	(1,442.7)	(1,350.7)	(1,120.7)
Net written premiums	1,350.5	1,506.1	2,896	2,587.7	2,577.8
Gross Amount	1,203.6	1,171.5	2,370.8	2,139.1	2,026.4
Assumed From Other Companies	755.7	776.9	1,617.2	1,479.2	1,612
Ceded	(671.9)	(621.2)	(1,299.3)	(1,207.8)	(1,110.9)
Net premiums earned	1,287.4	1,327.2	$ 2,688.7	$ 2,410.5	$ 2,527.5
Percentage of Amount Assumed to Net			60.10%	61.40%	63.80%
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5

Schedule V - Valuation and Qu_2

Schedule V - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premiums receivable from underwriting activities
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning  of Year	$ 30.2	$ 34	$ 23
Charged to Costs and Expenses	(5.2)	(3.8)	11
Charged to Other Accounts	0	0	0
Deductions	0	0	0
Balance at End of  Year	25	30.2	34
Reinsurance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning  of Year	0	0	0
Charged to Costs and Expenses	0
Charged to Other Accounts	0	0	0
Deductions	0	0	0
Balance at End of  Year	$ 0	$ 0	$ 0

Segment Reporting - Additiona_2

Segment Reporting - Additional Information - Narrative (Details) - segement	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Segment Reporting [Abstract]
Number of business segments	2	2

Segment Reporting - Summary o_3

Segment Reporting - Summary of Gross and Net Written and Earned Premiums, Underwriting Results, Ratios and Reserves for Each of Company's Business Segments (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Net written premiums	1,350.5	1,506.1	2,896	2,587.7	2,577.8
Gross earned premiums			3,988	3,618.3	3,638.4
Net earned premiums	1,287.4	1,327.2	2,688.7	2,410.5	2,527.5
Losses and loss adjustment expenses	717.1	767.7	1,680	1,693.3	1,840.8
Acquisition costs	192.9	216.5	431.8	414.1	465.7
General and administrative expenses	169	186.5	386.5	333.1	308
Underwriting income (loss)	208.4	156.5	190.4	(30)	(87)
Corporate Expenses	(53.1)	(37.5)	(71.7)	(64.3)	(70.2)
Non-operating expenses (1)	(10.6)	(3.6)	(36)	(20.6)	(32.7)
Net investment income (1)	129.4	88.7	188.1	147.5	154.6
Realized and unrealized investment gains	36.1	2.5	5	56.2	98.5
Realized and unrealized investment losses	(18.1)	(128.9)	(182.6)	(47.4)	(27.4)
Gain (Loss) on Extinguishment of Debt		0
Change in fair value of derivatives	19.6	(84.9)	(80.5)	(35.9)	(65.1)
Interest Expense, Debt	(42.9)	(9.1)	(43.7)	(14.3)	(33.9)
Net realized and unrealized foreign exchange gains	(13.7)	75.2	15.9	40	(13.8)
Other Nonoperating Income		2.9
Other Nonoperating Expense		(8.7)
Income (loss) from operations before income taxes	255.1	53.1	(27)	35.1	(38)
Income Tax Expense (Benefit)	(36.2)	(4.7)	78.1	(5.3)	(18.4)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Losses and loss adjustment expenses	7,740.9	7,511.8	7,710.9	7,611.8	7,165.3	$ 6,951.8
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total	$ 3,082.9	$ 2,505.3	$ 2,813.2	$ 4,313.7	$ 3,970.1	$ 4,632
Ratios
Loss ratio	55.70%	57.80%	62.50%	70.20%	72.80%
Acquisition cost ratio	15%	16.30%	16.10%	17.20%	18.40%
General and administrative expense ratio	13.10%	14.10%	14.40%	13.80%	12.20%
Expense ratio	28.10%	30.40%	30.50%	31%	30.60%
Combined ratio	83.80%	88.20%	93%	101.20%	103.40%
Gain (Loss) on Fair Value of Loan Notes, Issued by Variable Interest Entity		$ 0
Reinsurance
Segment Reporting Information [Line Items]
Net written premiums			$ 1,426.4	$ 1,199	$ 1,297.7
Net earned premiums			1,251.8	1,118.8	1,287.7
Losses and loss adjustment expenses	$ 1,441.2	$ 1,190.4	1,360.7	2,148.4	2,095.7
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total			$ 1,360.7	$ 2,148.4	$ 2,095.7
Ratios
Loss ratio	52%	61.40%	61.50%	63%	74.40%
Acquisition cost ratio	18.50%	20.70%	20.20%	19.80%	19.10%
General and administrative expense ratio	10.20%	11.60%	11.40%	10.80%	8.60%
Expense ratio	28.70%	32.30%	31.60%	30.60%	27.70%
Combined ratio	80.70%	93.70%	93.10%	93.60%	102.10%
Insurance
Segment Reporting Information [Line Items]
Net written premiums			$ 1,469.6	$ 1,388.7	$ 1,280.1
Net earned premiums			1,436.9	1,291.7	1,239.8
Losses and loss adjustment expenses	$ 1,641.7	$ 1,314.9	1,452.5	2,165.3	1,874.4
Liability for Unpaid Claims and Claims Adjustment Expense, Net, Total			$ 1,452.5	$ 2,165.3	$ 1,874.4
Ratios
Loss ratio	58.70%	54.90%	63.30%	76.50%	71.10%
Acquisition cost ratio	12.20%	12.70%	12.50%	14.90%	17.70%
General and administrative expense ratio	15.50%	16.10%	17%	16.40%	15.90%
Expense ratio	27.70%	28.80%	29.50%	31.30%	33.60%
Combined ratio	86.40%	83.70%	92.80%	107.80%	104.70%
Operating Segments | Reinsurance
Segment Reporting Information [Line Items]
Gross written premiums	$ 875.7	$ 1,045.6	$ 1,807	$ 1,597	$ 1,656.4
Net written premiums	605	783.7	1,426.4	1,199	1,297.7
Gross earned premiums			1,617.2	1,479.2	1,612
Net earned premiums	572	600.8	1,251.8	1,118.8	1,287.7
Losses and loss adjustment expenses	297.2	369	770.3	705.2	958.6
Acquisition costs	105.7	124.1	252.4	221.6	246
General and administrative expenses	58.4	69.7	142.5	121.3	110.8
Underwriting income (loss)	110.7	38	86.6	70.7	(27.7)
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Gross written premiums	1,249.5	1,305.7	2,531.7	2,341.4	2,042.1
Net written premiums	745.5	722.4	1,469.6	1,388.7	1,280.1
Gross earned premiums			2,370.8	2,139.1	2,026.4
Net earned premiums	715.4	726.4	1,436.9	1,291.7	1,239.8
Losses and loss adjustment expenses	419.9	398.7	909.7	988.1	882.2
Acquisition costs	87.2	92.4	179.4	192.5	219.7
General and administrative expenses	110.6	116.8	244	211.8	197.2
Underwriting income (loss)	$ 97.7	$ 118.5	$ 103.8	$ (100.7)	$ (59.3)

Investments - Summary of Inve_2

Investments - Summary of Investment Income (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ (134.7)	$ (93.5)	$ (198.4)	$ (159.2)	$ (167.3)
Investment expenses	(5.3)	(4.8)	(10.3)	(11.7)	(12.7)
Net investment income (1)	129.4	88.7	188.1	147.5	154.6
Fixed income securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(55.7)	(44.5)	(95.6)	(87.2)	(106.5)
Short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(1.6)	0	(0.6)	(0.1)	(0.8)
Short-term investment, Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(0.1)	0	(0.1)	0	(0.5)
Fixed term deposits (included in cash and cash equivalents)
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(17.3)	(0.5)	(6.6)	(0.7)	(6.4)
Catastrophe bonds — Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(1.1)	(0.1)	(0.3)	(0.9)	(1.4)
Privately-held investments — Trading
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	(21.5)	(8.8)	(24.3)	(18.2)	(20.9)
Other investments, at fair value
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	10.4	(20.7)	(13.9)	(21.9)	(2)
Fixed Income Securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ (47.8)	$ (18.9)	$ (57)	$ (30.2)	$ (32.8)

Investments - Net Realized an_2

Investments - Net Realized and Unrealized Investment Gains and Losses and Change in Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities - gross realized gains	$ 0.4	$ 1.4	$ 2.9	$ 22.7	$ 68.8
Fixed income securities - gross realizes (losses)	(6.9)	(29.9)	(58.4)	(3.6)	(1.8)
Net change in expected credit gains (losses)	3.7	(7.7)	(5)	(2.5)	0.4
Fixed income securities, trading - gross realized gains	0.3	0	0.2	12.2	18.2
Fixed income securities, trading, gross realizes (losses)	(1.1)	(0.2)	(1.8)	(2)	(3.8)
Privately-held investments net unrealized gains/(losses)	31	(89.6)	(113.9)	(23.4)	0
Catastrophe bonds	(0.6)	(0.1)	0.2	(0.8)	0
Total net realized and unrealized investment (losses)/gains recorded in the consolidated statement of operations	18	(126.4)	(177.6)	8.8	71.1
Change in available for sale net unrealized (losses)/gains:
Fixed income securities	12.3	(316)	(391.7)	(157.6)	108.5
Income tax benefit/(expense)	(1.6)	29.5	23.9	(0.3)	(0.5)
Change in unrealized (losses)/gains on investments	10.7	(286.5)	(367.8)	(157.9)	108
Cash and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities - gross realized gains	0.1	0.9	1	2	0.5
Fixed income securities - gross realizes (losses)	(0.1)	(0.2)	(0.5)	(0.8)	(0.4)
Fixed income securities, trading - gross realized gains	0.1	0	0	0.1	0.2
Fixed income securities, trading, gross realizes (losses)	(0.2)	0	0	(0.3)	(0.3)
Privately-held investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities, trading - gross realized gains	0.1	0.2	0.7	0.6	0
Fixed income securities, trading, gross realizes (losses)			(0.1)	(13.8)	0
Privately-held investments net unrealized gains/(losses)	9	1.3	2.5	(18.1)	20.4
Short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Fixed income securities - gross realizes (losses)	(0.2)	0
MVI
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment			0	0.1	(0.4)
Multi-Line Insurer
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment	$ 0.4	$ 0.1	(0.4)	0.2	0
Digital Re
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Income/(loss) from equity method investment			$ 0	$ 0	$ (0.3)

Investments - Cost, Gross Unr_3

Investments - Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available for Sale Investments in Fixed Income Maturities and Short-Term Investments (Details) $ in Millions	Jun. 30, 2023 USD ($) security Security	Dec. 31, 2022 USD ($)	Dec. 31, 2022 security	Dec. 31, 2022 Security	Dec. 31, 2021 USD ($) security Security
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	$ 3,908.2	$ 3,788.6			$ 4,881.6
Gross unrealized gains	2.4	3.6			95.3
Gross unrealized losses	(321.4)	(338.6)			(34.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(4)	(7.7)			(2.7)
Fixed income securities, available for sale amortized cost	4,231.2	4,131.3			4,823.5
0-12 months, Fair Market Value	1,175.6	2,321.4			2,014.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	32.5	145.4			30.9
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,758.3	3,645.1			2,086.6
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 321.4	339			$ 34.5
Number of Securities | security	1,193		1,166		644
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (288.9)	(193.6)			$ (3.6)
Total short-term investments — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross unrealized gains	0	0			0
Gross unrealized losses	0	(0.4)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Total fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	4,077.5	3,840.6			4,891.7
Gross unrealized gains	2.4	3.6			95.3
Gross unrealized losses	(321.4)	(339)			(34.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(4)	(7.7)			(2.7)
Fixed income securities, available for sale amortized cost	4,400.5	4,183.7			4,833.6
Fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
0-12 months, Fair Market Value	1,163.8	2,269.5			2,010.2
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	32.5	145			30.9
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,746.5	3,593.2			2,082.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 321.4	338.6			$ 34.5
Number of Securities | Security	1,188			1,165	637
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (288.9)	(193.6)			$ (3.6)
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
0-12 months, Fair Market Value	11.8	51.9			4.4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0.4			0
Over 12 months, Fair Market Value	0	0			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	11.8	51.9			4.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0	0.4			$ 0
Number of Securities	5		1	1	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	0			$ 0
U.S. government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,013.8	953			1,084.3
Gross unrealized gains	0	0			24
Gross unrealized losses	(51.1)	(50.7)			(5.9)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	1,064.9	1,003.7			1,066.2
0-12 months, Fair Market Value	494.8	741.1			309.1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	12.8	30.6			4
Over 12 months, Fair Market Value	519.1	203.4			29.3
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,013.9	944.5			338.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 51.1	50.7			$ 5.9
Number of Securities | security	105		118		51
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (38.3)	(20.1)			$ (1.9)
U.S. agency
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	8.2	8.8			21.5
Gross unrealized gains	0	0			0.8
Gross unrealized losses	(0.4)	(0.4)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	8.6	9.2			20.7
0-12 months, Fair Market Value	7	7.1			6.1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0.4	0.4			0
Over 12 months, Fair Market Value	1.1	1.7			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	8.1	8.8			6.1
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0.4	0.4			$ 0
Number of Securities | security	4		5		5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	0			$ 0
Municipal
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	149.5	149.5			82.6
Gross unrealized gains	0	0			2
Gross unrealized losses	(8.8)	(9.4)			(0.5)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(0.7)	(1)			(0.1)
Fixed income securities, available for sale amortized cost	159	159.9			81.2
0-12 months, Fair Market Value	90.9	133.1			29.7
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	3.7	7.1			0.5
Over 12 months, Fair Market Value	58.7	16.4			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	149.6	149.5			29.7
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8.8	9.4			$ 0.5
Number of Securities | security	60		59		20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (5.1)	(2.3)			$ 0
Corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,875.9	1,845			2,208.3
Gross unrealized gains	2.4	3.5			47.5
Gross unrealized losses	(155.2)	(169.1)			(13)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(3.2)	(6.3)			(2.3)
Fixed income securities, available for sale amortized cost	2,031.9	2,016.9			2,176.1
0-12 months, Fair Market Value	467.4	1,104.7			804.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	13.1	77.6			11.7
Over 12 months, Fair Market Value	1,254.7	568.2			23.6
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,722.1	1,672.9			828.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 155.2	169.1			$ 13
Number of Securities | security	727		701		400
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (142.1)	(91.5)			$ (1.3)
Non-U.S. government-backed corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	110.9	110.4			136.8
Gross unrealized gains	0	0			0.2
Gross unrealized losses	(8.7)	(8.8)			(1.9)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	(0.2)			0
Fixed income securities, available for sale amortized cost	119.6	119.4			138.5
0-12 months, Fair Market Value	5.2	11.3			114.4
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0.5			1.9
Over 12 months, Fair Market Value	105.7	99			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	110.9	110.3			114.4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8.7	8.8			$ 1.9
Number of Securities | security	16		16		10
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (8.7)	(8.3)			$ 0
Non-U.S government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	269.2	213.6			250.7
Gross unrealized gains	0	0.1			1.4
Gross unrealized losses	(12)	(11.5)			(1.2)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	(0.1)	(0.2)			(0.3)
Fixed income securities, available for sale amortized cost	281.3	225.2			250.8
0-12 months, Fair Market Value	80.1	63.8			181.8
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	1.2	2.9			1.2
Over 12 months, Fair Market Value	182.2	135.9			3.1
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	262.3	199.7			184.9
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 12	11.5			$ 1.2
Number of Securities | security	61		45		35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (10.8)	(8.6)			$ 0
Asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value					0.5
Gross unrealized gains					0
Gross unrealized losses					0
Debt Securities, Available-for-Sale, Allowance for Credit Loss					0
Fixed income securities, available for sale amortized cost					0.5
Non-agency commercial mortgage-backed securities
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	5.7	5.6			6.9
Gross unrealized gains	0	0			0.3
Gross unrealized losses	(0.9)	(1)			0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	6.6	6.6			6.6
0-12 months, Fair Market Value	0	5.6
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	1
Over 12 months, Fair Market Value	5.6	0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	5.6	5.6
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 0.9	1
Number of Securities | security	1		1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (0.9)	0
Agency mortgage-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	475	502.7			1,090
Gross unrealized gains	0	0			19.1
Gross unrealized losses	(84.3)	(87.7)			(12)
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0			0
Fixed income securities, available for sale amortized cost	559.3	590.4			1,082.9
0-12 months, Fair Market Value	18.4	202.8			564.5
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	1.3	24.9			11.6
Over 12 months, Fair Market Value	455.6	299.1			16
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	474	501.9			580.5
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 84.3	87.7			$ 12
Number of Securities | security	214		220		116
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (83)	(62.8)			$ (0.4)
Total short-term investments — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	169.3	52			10.1
Fixed income securities, available for sale amortized cost	$ 169.3	$ 52.4			$ 10.1

Investments - Cost, Gross Unr_4

Investments - Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Trading Investments in Fixed Income Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Trading Securities and Other Trading Items [Line Items]
Debt Securities, Trading, Amortized Cost	$ 1,552.7	$ 1,576.7	$ 1,155.5
High yield loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(1.2)	(0.2)	(0.1)
Gross Unrealized Losses	0.7	2.1	0.4
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	86.6	88.3	76.9
Debt Securities, Trading, Amortized Cost	86.1	90.2	77.2
Fixed income securities - trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(2.5)	(0.7)	(6.2)
Gross Unrealized Losses	76.7	101.9	4.2
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	1,478.5	1,475.5	1,157.5
Debt Securities, Trading, Amortized Cost	1,552.7	1,576.7	1,155.5
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0	0	0
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	11	6.3	2
Debt Securities, Trading, Amortized Cost	11	6.3	2
Catastrophe Bonds
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0	2.2	1.9
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	2.4	2.9	3.4
Debt Securities, Trading, Amortized Cost	2.4	5.1	5.3
Commercial mortgage loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(1.3)	(0.6)	(0.4)
Gross Unrealized Losses	11.8	1.1	0.9
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	295	312.1	211.5
Debt Securities, Trading, Amortized Cost	305.5	312.6	212
Middle market loans
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	2	2.1	1.5
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	102.1	106.9	65.4
Debt Securities, Trading, Amortized Cost	104.1	109	66.9
Securities, asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	1.1	2	0.2
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	58.4	66.8	26.6
Debt Securities, Trading, Amortized Cost	59.5	68.8	26.8
Global corporates securities
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0.1	0.1
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	14.8	15
Debt Securities, Trading, Amortized Cost	14.9	15.1
Equity securities — Trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	(0.1)
Gross Unrealized Losses	0	0	0
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	12.1	6.6	3.6
Debt Securities, Trading, Amortized Cost	12.1	6.6	3.5
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)		25.6
Debt Securities, Trading, Amortized Cost		25.6
Privately-held investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(1.3)	(0.6)	(0.5)
Gross Unrealized Losses	15	5.3	2.6
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	482.4	533	307.1
Debt Securities, Trading, Amortized Cost	496.1	537.7	309.2
Total - Trading
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(3.8)	(1.3)	(6.7)
Gross Unrealized Losses	91.7	109.4	8.7
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	1,974.3	2,017.7	1,470
Debt Securities, Trading, Amortized Cost	2,062.2	2,125.8	1,472
U.S. government
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	(0.6)
Gross Unrealized Losses	6.9	6.3	0.2
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	235	261.6	116.3
Debt Securities, Trading, Amortized Cost	241.9	267.9	115.9
Municipal
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	(0.1)
Gross Unrealized Losses	0.3	0.3	0
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	3.1	3.6	4
Debt Securities, Trading, Amortized Cost	3.4	3.9	3.9
Corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(0.3)	(0.3)	(1.9)
Gross Unrealized Losses	11.8	13.5	0.8
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	165.4	162.1	96.8
Debt Securities, Trading, Amortized Cost	176.9	175.3	95.7
Non-U.S government
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	1.7	1.8	0.4
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	34.1	30.4	34.5
Debt Securities, Trading, Amortized Cost	35.8	32.2	34.9
Asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	(1)	(0.2)	(3.3)
Gross Unrealized Losses	51.6	74	1.9
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	924.6	896.5	785.7
Debt Securities, Trading, Amortized Cost	975.2	970.3	784.3
Agency mortgage-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	(0.2)
Gross Unrealized Losses	3.2	3.3	0.3
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	20.1	21.4	30.2
Debt Securities, Trading, Amortized Cost	23.3	24.7	30.3
Non-U.S. government-backed corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	0.5	0.6	0.2
Fixed income maturities, trading at fair value (amortized cost — $1,106.6 and $1,205.0)	9.6	11.6	13.1
Debt Securities, Trading, Amortized Cost	$ 10.1	$ 12.2	$ 13.3

Investments Investments - Dis_2

Investments Investments - Distribution of Commercial Mortgage and Middle Market Loans (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Middle market loans
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 102.1	$ 106.9	$ 65.4
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Apartment
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 107.8	$ 115.3	$ 101.6
Concentration risk percentage	36.60%	36.90%	48.10%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Hotel
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 98.1	$ 108	$ 68.8
Concentration risk percentage	33.30%	34.60%	32.50%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Office building
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 45.9	$ 42.1	$ 33.9
Concentration risk percentage	15.50%	13.50%	16%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Other commercial
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 37.9	$ 41.4	$ 7.2
Concentration risk percentage	12.80%	13.30%	3.40%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 3.3	$ 3.3	$ 0
Concentration risk percentage	1.10%	1.10%	0%
Investment, Net Carrying Value | Commercial mortgage loans | Product Concentration Risk | Industrial
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 2	$ 2	$ 0
Concentration risk percentage	0.70%	0.60%	0%
Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Materials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 20	$ 19.8	$ 20.9
Concentration risk percentage	19.60%	18.50%	32%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Financials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 48.3	$ 53.1	$ 6.1
Concentration risk percentage	47.30%	49.70%	9.30%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Industrials
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 18.6	$ 18.7	$ 18.7
Concentration risk percentage	18.20%	17.50%	28.50%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Consumer discretionary
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 4.9	$ 4.9	$ 4.3
Concentration risk percentage	4.80%	4.60%	6.60%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Energy
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 5.6	$ 5.7	$ 5.6
Concentration risk percentage	5.50%	5.30%	8.60%
Investment, Net Carrying Value | Middle market loans | Product Concentration Risk | Information technology
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 4.7	$ 4.7	$ 4.9
Concentration risk percentage	4.60%	4.40%	7.50%
Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Concentration risk percentage	100%	100%	100%
U.S. | Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 263.6	$ 269.8	$ 183.7
Concentration risk percentage	89.40%	86.40%	86.90%
U.S. | Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 59.4	$ 64.1	$ 56.2
Concentration risk percentage	58.20%	59.90%	85.90%
International | Investment, Net Carrying Value | Commercial mortgage loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 31.4	$ 42.3	$ 27.8
Concentration risk percentage	10.60%	13.60%	13.10%
International | Investment, Net Carrying Value | Middle market loans | Geographic Concentration Risk
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Fair market value, trading	$ 42.7	$ 42.8	$ 9.2
Concentration risk percentage	41.80%	40.10%	14.10%

Investments Investments - Loa_2

Investments Investments - Loan-to-Value Ratios (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Commercial mortgage loans | Less than 50 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	47.5	41.1	0
Commercial mortgage loans | 50 to 60 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	227.3	248.3	131.2
Commercial mortgage loans | 61 to 70 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	20.2	22.7	80.3
Middle market loans
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	102.1	106.9	65.4
Middle market loans | Less than 50 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	63.5	63.5	11
Middle market loans | 50 to 60 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	23.3	16.4	9.2
Middle market loans | 61 to 70 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
Fair market value, trading	$ 15.3	$ 27	$ 15.8

Investments Investments - Deb_2

Investments Investments - Debt Service and Fixed Charge Coverage Ratios (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 295	$ 312.1	$ 211.5
Commercial mortgage loans	295	292.2	147.5
Delinquent amount of loans at end of period	0	19.9	64
Commercial mortgage loans | Nonperforming loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0	0	0
Commercial mortgage loans | Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	47.5	41.1	0
Commercial mortgage loans | 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	227.3	248.3	131.2
Commercial mortgage loans | 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	20.2	22.7	80.3
Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	102.1	106.9	65.4
Middle market loans | Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	63.5	63.5	11
Middle market loans | 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	23.3	16.4	9.2
Middle market loans | 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	15.3	27	15.8
Greater than 1.20x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	112.3	106.1	66.3
Greater than 1.20x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	78.9	95.2	25.8
1.00 - 1.20x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	182.7	186.1	62.4
1.00 - 1.20x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	3.8	3.8	22.8
Less than 1.00x | Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0	0	18.8
Less than 1.00x | Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 19.4	$ 7.9	$ 16.8

Investments - Other Investmen_2

Investments - Other Investments (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2021	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		$ 6.2	$ 3.9	$ 0.9
Investment in the period		0.4	2	3.2
Closing value of investment, ending balance		7	6.2	3.9
Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0.4	0.3	0.3
Fair Value, Recurring [Member] | Real estate fund (Dec 2017)
Equity Method Investment, Aggregate Cost [Roll Forward]
Investments, fair value		125.2	134.6	129.9
MVI
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		0.8	0.5	0
Investment in the period	$ 0.8	0	0.4	0.4
Closing value of investment, ending balance		0.8	0.8	0.5
MVI | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0	(0.1)	0.1
Digital Re
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		0.2	0.2	0.4
Investment in the period		0	0	0.3
Closing value of investment, ending balance		0.2	0.2	0.2
Digital Re | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		0	0	0
Multi-Line Insurer
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance		5.2	3.2	0.5
Investment in the period		0.4	1.6	2.5
Closing value of investment, ending balance		6	5.2	3.2
Multi-Line Insurer | Equity Method Investment, Nonconsolidated Investee, Other
Equity Method Investment, Aggregate Cost [Roll Forward]
Unrealized Gain (Loss) on Investments		$ 0.4	$ 0.4	$ 0.2

Investments - Summary of Fixe_2

Investments - Summary of Fixed Maturities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 4,231.2	$ 4,131.3	$ 4,823.5
Fair market value	3,908.2	3,788.6	4,881.6
Total fixed income securities — Available for sale
Debt Securities, Available-for-sale [Line Items]
Due one year or less, Cost or Amortized Cost	242.4	179.1	545.1
Due after one year through five years, Cost or Amortized Cost	2,736.2	2,526.9	2,057.2
Due after five years through ten years, Cost or Amortized Cost	684.9	815.1	1,090.5
Due after ten years, Cost or Amortized Cost	1.8	13.2	40.7
Fixed income securities, available for sale amortized cost	3,665.3	3,534.3	3,733.5
Due one year or less, Fair Market Value	$ 236.5	$ 176	$ 549
Available For Sale Securities Debt Maturities Within One Year Average Ratings By Maturity	AA	AA+	AA-
Due after one year through five years, Fair Market Value	$ 2,594.7	$ 2,385.7	$ 2,087.5
Available For Sale Securities Debt Maturities After One Through Five Years Average Ratings By Maturity	AA-	AA-	AA-
Due after five years through ten years, Fair Market Value	$ 595.2	$ 707.7	$ 1,106.3
Available For Sale Securities Debt Maturities After Five Through Ten Years Average Ratings By Maturity	A+	A+	A+
Due after ten years, Fair Market Value	$ 1.1	$ 10.9	$ 41.4
Available For Sale Securities Debt Maturities After Ten Years Average Ratings By Maturity	BB	A-	A-
Fair market value	$ 3,427.5	$ 3,280.3	$ 3,784.2
Agency mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	559.3	590.4	1,082.9
Fair market value	$ 475	$ 502.7	$ 1,090
Available For Sale Securities Average Ratings By Maturity	AA+	AA+	AA+
Non-agency commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 6.6	$ 6.6	$ 6.6
Fair market value	$ 5.7	$ 5.6	$ 6.9
Available For Sale Securities Average Ratings By Maturity	AA+	AA+	AA+
Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost	$ 4,231.2	$ 4,131.3	$ 4,823.5
Fair market value	$ 3,908.2	$ 3,788.6	4,881.6
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fixed income securities, available for sale amortized cost			0.5
Fair market value			$ 0.5
Available For Sale Securities Average Ratings By Maturity			AAA

Investments - Aggregate Fair _2

Investments - Aggregate Fair Value and Gross Unrealized Loss by Type of Security (Details) $ in Millions	Jun. 30, 2023 USD ($) security Security	Dec. 31, 2022 USD ($)	Dec. 31, 2022 security	Dec. 31, 2022 Security	Dec. 31, 2021 USD ($) security Security
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 1,175.6	$ 2,321.4			$ 2,014.6
Gross unrealized losses, less than twelve months	(32.5)	(145.4)			(30.9)
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Over 12 months, Gross Unrealized Losses	(288.9)	(193.6)			(3.6)
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,758.3	3,645.1			2,086.6
Total, Gross Unrealized Losses	$ (321.4)	(339)			$ (34.5)
Number of Securities | security	1,193		1,166		644
Fixed income securities — Available for sale
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 1,163.8	2,269.5			$ 2,010.2
Gross unrealized losses, less than twelve months	(32.5)	(145)			(30.9)
Over 12 months, Fair Market Value	2,582.7	1,323.7			72
Over 12 months, Gross Unrealized Losses	(288.9)	(193.6)			(3.6)
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	3,746.5	3,593.2			2,082.2
Total, Gross Unrealized Losses	$ (321.4)	(338.6)			$ (34.5)
Number of Securities | Security	1,188			1,165	637
Short-term investments
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 11.8	51.9			$ 4.4
Gross unrealized losses, less than twelve months	0	(0.4)			0
Over 12 months, Fair Market Value	0	0			0
Over 12 months, Gross Unrealized Losses	0	0			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	11.8	51.9			4.4
Total, Gross Unrealized Losses	$ 0	(0.4)			$ 0
Number of Securities	5		1	1	7
U.S. government
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 494.8	741.1			$ 309.1
Gross unrealized losses, less than twelve months	(12.8)	(30.6)			(4)
Over 12 months, Fair Market Value	519.1	203.4			29.3
Over 12 months, Gross Unrealized Losses	(38.3)	(20.1)			(1.9)
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,013.9	944.5			338.4
Total, Gross Unrealized Losses	$ (51.1)	(50.7)			$ (5.9)
Number of Securities | security	105		118		51
U.S. agency
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 7	7.1			$ 6.1
Gross unrealized losses, less than twelve months	(0.4)	(0.4)			0
Over 12 months, Fair Market Value	1.1	1.7			0
Over 12 months, Gross Unrealized Losses	0	0			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	8.1	8.8			6.1
Total, Gross Unrealized Losses	$ (0.4)	(0.4)			$ 0
Number of Securities | security	4		5		5
Municipal
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 90.9	133.1			$ 29.7
Gross unrealized losses, less than twelve months	(3.7)	(7.1)			(0.5)
Over 12 months, Fair Market Value	58.7	16.4			0
Over 12 months, Gross Unrealized Losses	(5.1)	(2.3)			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	149.6	149.5			29.7
Total, Gross Unrealized Losses	$ (8.8)	(9.4)			$ (0.5)
Number of Securities | security	60		59		20
Corporate
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 467.4	1,104.7			$ 804.6
Gross unrealized losses, less than twelve months	(13.1)	(77.6)			(11.7)
Over 12 months, Fair Market Value	1,254.7	568.2			23.6
Over 12 months, Gross Unrealized Losses	(142.1)	(91.5)			(1.3)
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	1,722.1	1,672.9			828.2
Total, Gross Unrealized Losses	$ (155.2)	(169.1)			$ (13)
Number of Securities | security	727		701		400
Non-U.S. government-backed corporate
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 5.2	11.3			$ 114.4
Gross unrealized losses, less than twelve months	0	(0.5)			(1.9)
Over 12 months, Fair Market Value	105.7	99			0
Over 12 months, Gross Unrealized Losses	(8.7)	(8.3)			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	110.9	110.3			114.4
Total, Gross Unrealized Losses	$ (8.7)	(8.8)			$ (1.9)
Number of Securities | security	16		16		10
Non-U.S government
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 80.1	63.8			$ 181.8
Gross unrealized losses, less than twelve months	(1.2)	(2.9)			(1.2)
Over 12 months, Fair Market Value	182.2	135.9			3.1
Over 12 months, Gross Unrealized Losses	(10.8)	(8.6)			0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	262.3	199.7			184.9
Total, Gross Unrealized Losses	$ (12)	(11.5)			$ (1.2)
Number of Securities | security	61		45		35
Non-agency commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 0	5.6
Gross unrealized losses, less than twelve months	0	(1)
Over 12 months, Fair Market Value	5.6	0
Over 12 months, Gross Unrealized Losses	(0.9)	0
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	5.6	5.6
Total, Gross Unrealized Losses	$ (0.9)	(1)
Number of Securities | security	1		1
Agency mortgage-backed
Debt Securities, Available-for-sale [Line Items]
0-12 months, Fair Market Value	$ 18.4	202.8			$ 564.5
Gross unrealized losses, less than twelve months	(1.3)	(24.9)			(11.6)
Over 12 months, Fair Market Value	455.6	299.1			16
Over 12 months, Gross Unrealized Losses	(83)	(62.8)			(0.4)
Debt Securities, Available for Sale, Continuous Loss Position, Fair Market Value	474	501.9			580.5
Total, Gross Unrealized Losses	$ (84.3)	$ (87.7)			$ (12)
Number of Securities | security	214		220		116

Investments - Additional Info_2

Investments - Additional Information (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 05, 2022	Apr. 01, 2022	Sep. 30, 2021	Dec. 23, 2019	Dec. 20, 2017	Jan. 01, 2017
Gain (Loss) on Securities [Line Items]
Catastrophe bonds, trading, cost		$ 2.4		$ 2.9	$ 3.4
Investment in the period		0.4		2	3.2
Equity method investment, aggregate cost		7		6.2	3.9	$ 0.9
Other investments, at fair value (2)		213.4		221.3	151.3
Restricted assets		266.5		471.3	539.8
Investment funded		0		0
Available-for-sale investment, allowance for credit loss, increase (decrease)		(3.7)		5	2.5
Investment, Identifier [Axis]: Unfunded Commitment, Apollo Real Estate Fund
Gain (Loss) on Securities [Line Items]
Unfunded commitment		5.3		5.3
Investment, Identifier [Axis]: Unfunded Commitment, Infrastructure fund
Gain (Loss) on Securities [Line Items]
Unfunded commitment		6.4		8.4
Investment, Identifier [Axis]: Unfunded Commitment, Real Estate Fund (Sept 2021)
Gain (Loss) on Securities [Line Items]
Unfunded commitment		3.3		3.3
Fair Value, Recurring [Member] | Apollo real estate fund
Gain (Loss) on Securities [Line Items]
Other investments, at fair value (2)		22.9		25.3
Real estate fund | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		213.4		221.3	151.3
Commercial mortgage loans
Gain (Loss) on Securities [Line Items]
Fair market value, trading		295		312.1	211.5
Middle market loans
Gain (Loss) on Securities [Line Items]
Fair market value, trading		102.1		106.9	65.4
Privately-held investments
Gain (Loss) on Securities [Line Items]
Fair market value, trading		482.4		533	307.1
Real estate fund (Dec 2017) | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		125.2		134.6	129.9
Real estate fund (Sept 2021) | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		39.2		40.6	21.4
Infrastructure fund | Fair Value, Recurring [Member]
Gain (Loss) on Securities [Line Items]
Investments, fair value		11.7		8.2
MVI
Gain (Loss) on Securities [Line Items]
Investment in the period	$ 0.8	0		0.4	0.4
Equity method investment, aggregate cost		0.8		0.8	0.5	0
Gross realized and unrealized gains (loss)				0	0.1	(0.4)
Digital Re
Gain (Loss) on Securities [Line Items]
Investment in the period		0		0	0.3
Equity method investment, ownership percentage												49%
Equity method investment, aggregate cost		0.2		0.2	0.2	0.4						$ 2.3
Gross realized and unrealized gains (loss)				0	0	(0.3)
Multi-Line Insurer
Gain (Loss) on Securities [Line Items]
Investment in the period		0.4		1.6	2.5
Equity method investment, aggregate cost		6		5.2	3.2	0.5
Other investments, at fair value (2)										$ 5
Gross realized and unrealized gains (loss)		0.4	$ 0.1	(0.4)	0.2	$ 0
Limited Partner | Real estate fund
Gain (Loss) on Securities [Line Items]
Other investments, at fair value (2)		$ 213.4		$ 221.3	$ 151.3
Restricted assets								$ 10	$ 20		$ 100
Limited Partner | Real estate fund | Apollo real estate fund
Gain (Loss) on Securities [Line Items]
Restricted assets								$ 30
Limited Partner | Infrastructure fund
Gain (Loss) on Securities [Line Items]
Restricted assets							$ 15

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Assets Measured on Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Catastrophe Bonds, Fair Value Disclosure	$ 2.4	$ 5.1	$ 5.3
Derivatives at fair value	17.2	56.2	12.9
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	6,245.6	6,100.9	6,512.6
Recurring | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value	17.2	56.2	12.9
Recurring | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(13.4)	(3.2)	(13.3)
Recurring | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(23.4)	(31.7)
Recurring | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	5.7	5.6
Recurring | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3,908.2	3,788.6	4,881.6
Recurring | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	169.3	52	10.1
Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,478.5	1,475.5	1,157.5
Privately-held Investments, at fair value	482.4	533	307.1
Catastrophe Bonds, Fair Value Disclosure	2.4	2.9	3.4
Recurring | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	11	6.3	2
Recurring | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	213.4	221.3	151.3
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	1,632.5	1,428.7	1,384.5
Recurring | Level 1 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value		0	0
Recurring | Level 1 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0	0
Recurring | Level 1 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0
Recurring | Level 1 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Recurring | Level 1 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,206.5	1,098.3	1,248.7
Recurring | Level 1 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	169.2	51.9	6.5
Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	247.7	272.2	128.2
Privately-held Investments, at fair value	0	0	0
Catastrophe Bonds, Fair Value Disclosure	0	0	0
Recurring | Level 1 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.1	6.3	1.1
Recurring | Level 1 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	3,940.7	3,949.6	4,669.7
Recurring | Level 2 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value	17.2	56.2	12.9
Recurring | Level 2 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(13.4)	(3.2)	(13.3)
Recurring | Level 2 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0
Recurring | Level 2 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	5.7	5.6
Recurring | Level 2 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	2,701.7	2,690.3	3,632.9
Recurring | Level 2 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0.1	0.1	3.6
Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,230.8	1,203.3	1,029.3
Privately-held Investments, at fair value	0	0	0
Catastrophe Bonds, Fair Value Disclosure	2.4	2.9	3.4
Recurring | Level 2 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1.9	0	0.9
Recurring | Level 2 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	459	501.3	307.1
Recurring | Level 3 | Derivatives at fair value | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives at fair value		0	0
Recurring | Level 3 | Liabilities under derivative contracts | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	0	0	0
Recurring | Level 3 | Liabilities under derivative contracts | Loss Portfolio Transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities under derivative contracts, fair value	(23.4)	(31.7)
Recurring | Level 3 | Total fixed income securities — Available for sale | Non-agency commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0
Recurring | Level 3 | Fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Privately-held Investments, at fair value	482.4	533	307.1
Catastrophe Bonds, Fair Value Disclosure	0	0	0
Recurring | Level 3 | Short-term investments trading at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Recurring | Level 3 | Real estate fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,013.8	953	1,084.3
U.S. government | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	235	261.6	116.3
U.S. government | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,013.8	953	1,084.3
U.S. government | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	235	261.6	116.3
U.S. government | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. government | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. agency | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	8.2	8.8	21.5
U.S. agency | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
U.S. agency | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	8.2	8.8	21.5
U.S. agency | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	149.5	149.5	82.6
Municipal | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3.1	3.6	4
Municipal | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	149.5	149.5	82.6
Municipal | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	3.1	3.6	4
Municipal | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Municipal | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,875.9	1,845	2,208.3
Corporate | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	165.4	162.1	96.8
Corporate | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	1,875.9	1,845	2,208.3
Corporate | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	165.4	162.1	96.8
Corporate | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Corporate | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	110.9	110.4	136.8
Non-U.S. government-backed corporate | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.6	11.6	13.1
Non-U.S. government-backed corporate | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	110.9	110.4	136.8
Non-U.S. government-backed corporate | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	9.6	11.6	13.1
Non-U.S. government-backed corporate | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S. government-backed corporate | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S government | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	269.2	213.6	250.7
Non-U.S government | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	34.1	30.4	34.5
Non-U.S government | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	192.7	145.3	164.4
Non-U.S government | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	12.7	10.6	11.9
Non-U.S government | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	76.5	68.3	86.3
Non-U.S government | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	21.4	19.8	22.6
Non-U.S government | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-U.S government | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Asset-backed | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0.5
Asset-backed | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	924.6	896.5	785.7
Asset-backed | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Asset-backed | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Asset-backed | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0.5
Asset-backed | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	924.6	896.5	785.7
Asset-backed | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Asset-backed | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Non-agency commercial mortgage-backed securities | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		5.6	6.9
Non-agency commercial mortgage-backed securities | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Non-agency commercial mortgage-backed securities | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		5.6	6.9
Non-agency commercial mortgage-backed securities | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		0	0
Agency mortgage-backed | Recurring | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	475	502.7	1,090
Agency mortgage-backed | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	20.1	21.4	30.2
Agency mortgage-backed | Recurring | Level 1 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 2 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	475	502.7	1,090
Agency mortgage-backed | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	20.1	21.4	30.2
Agency mortgage-backed | Recurring | Level 3 | Total fixed income securities — Available for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
Agency mortgage-backed | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
High yield loans | Recurring | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	86.6	88.3	76.9
High yield loans | Recurring | Level 1 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	0	0	0
High yield loans | Recurring | Level 2 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	86.6	88.3	76.9
High yield loans | Recurring | Level 3 | Held for trading financial assets, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	$ 0	$ 0	$ 0

Fair Value Measurements Fair _2

Fair Value Measurements Fair Value Measurements - Reconciliation of Level 3 Assets and Liabilities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Accumulated other comprehensive (loss)
Commercial mortgage loans
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	$ 312.1	$ 211.5
Balance at the end of the year	295	312.1	$ 211.5
Middle market loans
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.4
Balance at the end of the year	102.1	106.9	65.4
Equity securities
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6
Balance at the end of the year	12.1	6.6	3.6
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6
Balance at the end of the year		25.6
Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(13.7)	(4.6)	(2.2)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	533	307.1
Balance at the end of the year	482.4	533	307.1
Recurring | Level 3 | Liability
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	(31.7)	0
Liability purchases	0	(17.2)
Liability transfers	0	0
Liability sales	0	0
Liability, increase (decrease) in fv included in net income	8.3	(14.5)
Balance at the end of the period	(23.4)	(31.7)	0
Change in unrealized gains or losses	0	0
Recurring | Level 3 | Liability | Loss Portfolio Transfer
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	(31.7)	0
Liability purchases	0	(17.2)
Liability transfers	0	0
Liability sales	0	0
Liability, increase (decrease) in fv included in net income		(14.5)
Balance at the end of the period	(23.4)	(31.7)	0
Change in unrealized gains or losses	0	0
Recurring | Commercial mortgage loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(10.5)	(0.5)	(0.5)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	312.1	211.5
Balance at the end of the year	295	312.1	211.5
Recurring | Middle market loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(2)	(2.1)	(1.5)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.3
Balance at the end of the year	102.1	106.9	65.3
Recurring | Asset-backed | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(1.1)	(2)	(0.2)
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	66.8	26.7
Balance at the end of the year	58.4	66.8	26.7
Recurring | Global corporate securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	(0.1)	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	15
Balance at the end of the year	14.8	15
Recurring | Equity securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	0	0	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6
Balance at the end of the year	12.1	6.6	3.6
Recurring | Preference shares | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)			0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year		0
Balance at the end of the year			0
Recurring | Short-term investments | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in unrealized investment gains (losses)	0	0
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6
Balance at the end of the year	0	25.6
Assets | Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	533	307.1	299.3
Purchases and issuances	23	378.2	205.1
Settlements and sales	(58.4)	(147.4)	(182)
Increase (decrease) in fair value included in net income	(8.5)	(4.9)	4.2
Balance at the end of the year		533	307.1
Transfers in/(out)	(6.7)	0	(19.5)
Assets | Recurring | Commercial mortgage loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	312.1	211.5	163.6
Purchases and issuances	15.9	215.7	169.9
Settlements and sales	(23.2)	(113.1)	(122.5)
Increase (decrease) in fair value included in net income	(9.8)	(2)	0.5
Balance at the end of the year		312.1	211.5
Transfers in/(out)	0	0	0
Assets | Recurring | Middle market loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	106.9	65.3	112.1
Purchases and issuances	0.1	61.8	5.6
Settlements and sales	(5.4)	(19.3)	(56.1)
Increase (decrease) in fair value included in net income	0.5	(0.9)	3.7
Balance at the end of the year		106.9	65.3
Transfers in/(out)	0	0	0
Assets | Recurring | Asset-backed | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	66.8	26.7	18.6
Purchases and issuances	0	54.5	10
Settlements and sales	(3.8)	(12.6)	(1.8)
Increase (decrease) in fair value included in net income	0.9	(1.8)	(0.1)
Balance at the end of the year		66.8	26.7
Transfers in/(out)	(5.5)	0	0
Assets | Recurring | Global corporate securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	15	0
Purchases and issuances	0	15.1
Settlements and sales	(0.2)	0
Increase (decrease) in fair value included in net income	0	(0.1)
Balance at the end of the year		15	0
Transfers in/(out)	0	0
Assets | Recurring | Equity securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	6.6	3.6	5
Purchases and issuances	7	5.5	0.1
Settlements and sales	(0.2)	(2.4)	(1.6)
Increase (decrease) in fair value included in net income	(0.1)	(0.1)	0.1
Balance at the end of the year		6.6	3.6
Transfers in/(out)	(1.2)	0	0
Assets | Recurring | Preference shares | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year			0
Purchases and issuances			19.5
Settlements and sales			0
Increase (decrease) in fair value included in net income			0
Transfers in/(out)		0	(19.5)
Assets | Recurring | Short-term investments | Level 3
Fair Value, Assets Measured on Recurring Basis, Calculation [Roll Forward]
Balance at the beginning of the year	25.6	0
Purchases and issuances	0	25.6
Settlements and sales	(25.6)	0
Increase (decrease) in fair value included in net income	0	0
Balance at the end of the year		25.6	$ 0
Transfers in/(out)	$ 0	$ 0

Fair Value Measurements - Inp_2

Fair Value Measurements - Inputs Used (Details) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross written premiums	$ 2,125.2	$ 2,351.3	$ 4,338.7	$ 3,938.4	$ 3,698.5
Held for trading financial assets, at fair value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	482.4		533	307.1
Held for trading financial assets, at fair value | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 482.4		$ 533	$ 307.1
Discounted cash flow | Commercial mortgage loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.037		0.039
Discounted cash flow | Commercial mortgage loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.112		0.094
Discounted cash flow | Commercial mortgage loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.062		0.053
Discounted cash flow | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 270		$ 200.7
Discounted cash flow | Middle market loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.058		0.074
Discounted cash flow | Middle market loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.093		0.185
Discounted cash flow | Middle market loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.068		0.099
Discounted cash flow | Middle market loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 58.4		$ 106.9
Discounted cash flow | Asset-backed | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.064		0.058
Discounted cash flow | Asset-backed | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.074		0.093
Discounted cash flow | Asset-backed | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.064		0.067
Discounted cash flow | Asset-backed | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 14.8
Discounted cash flow | Global corporate securities | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.086		0.064
Discounted cash flow | Global corporate securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 12.1		$ 15
Discounted cash flow | Short-term investments | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	482.4
Transaction value | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 25		85.8
Liquidation method | Commercial mortgage loans | Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.076
Liquidation method | Commercial mortgage loans | Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.209
Liquidation method | Commercial mortgage loans | Weighted Average | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement inputs	0.108
Liquidation method | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			25.6
Recovery approach | Commercial mortgage loans | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 102.1
Recovery approach | Asset-backed | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value			$ 66.8

Fair Value Measurements - Add_2

Fair Value Measurements - Additional Information - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) quotesPerInvestment	Dec. 31, 2022 USD ($) quotesPerInvestment	Dec. 31, 2021 USD ($) quotesPerInvestment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Quotes per fixed income investment | quotesPerInvestment	2.8	2.9	3
Assets | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers in/(out)	$ (6.7)	$ 0	$ (19.5)
Settlements and sales	(58.4)	(147.4)	(182)
Held for trading financial assets, at fair value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	482.4	533	307.1
Held for trading financial assets, at fair value | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held Investments, at fair value	$ 482.4	$ 533	$ 307.1

Reinsurance - Summary of Assu_2

Reinsurance - Summary of Assumed and Ceded Reinsurance on Premiums Written, Premiums Earned and Insurance Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premiums written:
Direct	$ 1,249.5	$ 1,305.7	$ 2,531.7	$ 2,341.4	$ 2,042.1
Assumed	875.7	1,045.6	1,807	1,597	1,656.4
Ceded	(774.7)	(845.2)	(1,442.7)	(1,350.7)	(1,120.7)
Net written premiums	1,350.5	1,506.1	2,896	2,587.7	2,577.8
Premiums earned:
Direct	1,203.6	1,171.5	2,370.8	2,139.1	2,026.4
Assumed	755.7	776.9	1,617.2	1,479.2	1,612
Ceded	(671.9)	(621.2)	(1,299.3)	(1,207.8)	(1,110.9)
Net premiums earned	1,287.4	1,327.2	2,688.7	2,410.5	2,527.5
Insurance losses and loss adjustment expenses:
Direct	691.7	719.2	1,574.2	1,499.8	1,479.6
Assumed	353.4	402.4	939.5	1,000.6	1,134.5
Ceded	(328)	(353.9)	(833.7)	(807.1)	(773.3)
Losses and loss adjustment expenses	$ 717.1	$ 767.7	$ 1,680	$ 1,693.3	$ 1,840.8

Reinsurance - Additional Info_2

Reinsurance - Additional Information (Details) - USD ($) $ in Millions			6 Months Ended	12 Months Ended
	Oct. 01, 2022	Jan. 10, 2022	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	Dec. 31, 2020	Mar. 02, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year			$ 4,658	$ 4,897.7	$ 3,298.1	$ 5,006.5	$ 3,195.2
Reinsurance Recoverable, Allowance for Credit Loss			3.3	3.7	3.3		$ 3.8
Reinsurance Recoverable, Allowance for Credit Loss, Period Increase (Decrease)			$ (0.4)	$ 0.4	$ (0.5)
Reinsurance Contracts [Axis]: Funds withheld credited with interest for periods after October 1, 2022
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance Retention Policy, Retrocession Premium, Interest Rate	1.75%
Enstar
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 770
Enstar | Reinsurance Contracts [Axis]: LPT losses reinsured]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT net losses reinsured
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Event		$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT premium paid
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance Recoverables for Unpaid Claims and Claims Adjustment, Ceded Claims Gross		$ 3,160

Derivative Contracts - Fair V_2

Derivative Contracts - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 1,884	$ 1,675.3	$ 1,545.7
Cash collateral	2.7	3.7	2.1
Not Designated as Hedging Instrument | Derivatives at Fair Value | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	7.2	41.9	12.9
Derivative, Notional Amount	670.6	945.8	759.8
Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	(13.4)	(3.2)	(12.4)
Derivative, Notional Amount	1,213.4	729.5	785.9
Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Embedded Derivative Financial Instruments
Derivatives, Fair Value [Line Items]
Fair Value	(23.4)	(31.7)	0
Derivative, Notional Amount	0	0	0
Designated as Hedging Instrument | Derivatives at Fair Value | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value	10	14.3	0
Derivative, Notional Amount	$ 54.7	109.7	0
Designated as Hedging Instrument | Liabilities Under Derivative Contracts | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair Value		0	(0.9)
Derivative, Notional Amount		$ 0	$ 143.1

Derivative Contracts - Gain_(_2

Derivative Contracts - Gain/(Loss) Recognized in Income on Derivative (Details) - Foreign exchange contracts - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Not Designated as Hedging Instrument | Gain (loss) on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to net income from derivative instruments	$ 19.6	$ (84.9)	$ (80.5)	$ (35.9)
Designated as Hedging Instrument | General, administrative and corporate expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	(3.7)	2.8	5.9	(5.7)
Designated as Hedging Instrument | Net change from current period hedged transactions
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives	$ (4.3)	$ (6.4)	$ 15.4	$ (6.2)

Derivative Contracts - Additi_2

Derivative Contracts - Additional Information (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
	Oct. 01, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Reinsurance Contracts [Axis]: Funds withheld credited with interest for periods after October 1, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Reinsurance Retention Policy, Retrocession Premium, Interest Rate	1.75%
Level 3 | Liability | Fair Value, Recurring [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Liability, increase (decrease) in fv included in net income		$ 8.3		$ (14.5)
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange		1,884		1,675.3	$ 1,545.7
Foreign exchange contracts | Not Designated as Hedging Instrument | Derivative At Fair Value
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange		670.6		945.8	759.8
Foreign exchange contracts | Not Designated as Hedging Instrument | Liabilities Under Derivative Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange		1,213.4		729.5	785.9
Foreign exchange contracts | Designated as Hedging Instrument | Derivative At Fair Value
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange		54.7		109.7	0
Foreign exchange contracts | Designated as Hedging Instrument | Liabilities Under Derivative Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Purchase of US and foreign exchange				0	143.1
Foreign exchange contracts | Net change from current period hedged transactions | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives		(4.3)	$ (6.4)	15.4	(6.2)
Foreign exchange contracts | General, administrative and corporate expenses | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on foreign currency fair value hedge derivatives		(3.7)	2.8	5.9	(5.7)
Foreign exchange contracts | Gain (loss) on derivative instruments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to net income from derivative instruments		19.6	(84.9)	(80.5)	$ (35.9)
Loss Portfolio Transfer | Level 3 | Liability | Fair Value, Recurring [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Liability, increase (decrease) in fv included in net income				$ (14.5)
Loss Portfolio Transfer | Fair value of derivatives | Level 3 | Fair Value, Recurring [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Liability, increase (decrease) in fv included in net income		$ 8.3	$ 0

Reserves for Losses and Adju_11

Reserves for Losses and Adjustment Expenses - Reconciliation of Beginning and Ending Consolidated Loss and Loss Adjustment Expenses (LAE) Reserves (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
	Jan. 10, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 30, 2022	Mar. 02, 2020	Dec. 31, 2019
Insurance [Abstract]
Provision for losses and LAE, beginning balance		$ 7,710.9	$ 7,611.8	$ 7,611.8	$ 7,165.3	$ 6,951.8
Less reinsurance recoverable				(4,897.7)	(3,298.1)	(3,195.2)			$ (2,319.8)
Net losses and LAE reserves, beginning balance		2,813.2	4,313.7	4,313.7	3,970.1	4,632
Movement in net provision for losses and LAE for claims incurred:
Current year		723.5	775	1,651.9	1,648.2	1,841.7
Prior years		6.4	7.3	(28.1)	(45.1)	0.9
Total incurred		717.1	767.7	1,680	1,693.3	1,840.8
Net Losses and LAE payments for claims incurred:
Current year		(30.8)	(35.5)	(192.7)	(729.1)	(404.9)
Prior years		(438.6)	(616.9)	(1,098.4)	(580.7)	(1,359.7)
Total paid		(469.4)	(652.4)	(1,291.1)	(1,309.8)	(1,764.6)
Foreign exchange (gains)/losses		22	(83.6)	(49.3)	(39.9)	80.4
Net losses and LAE reserves, ending balance		3,082.9	2,505.3	2,813.2	4,313.7	3,970.1
Plus reinsurance recoverable on unpaid losses at the end of the year		4,658	5,006.5	4,897.7	3,298.1	3,195.2
Provision for losses and LAE at the end of the year		7,740.9	7,511.8	7,710.9	7,611.8	7,165.3
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Net loss and LAE expenses disposed (1)		0	1,840.1	1,840.1	0	818.5
Plus reinsurance recoverable on unpaid losses at the end of the year		4,658	5,006.5	4,897.7	3,298.1	3,195.2
Reinsurance Contracts [Axis]: LPT
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable total							$ 2,610.1
Insurance
Insurance [Abstract]
Provision for losses and LAE, beginning balance		1,452.5	2,165.3	2,165.3	1,874.4
Net losses and LAE reserves, beginning balance		1,452.5	2,165.3	2,165.3	1,874.4
Movement in net provision for losses and LAE for claims incurred:
Prior years		(8.5)		(86.9)
Net Losses and LAE payments for claims incurred:
Net losses and LAE reserves, ending balance				1,452.5	2,165.3	1,874.4
Provision for losses and LAE at the end of the year		1,641.7	$ 1,314.9	$ 1,452.5	$ 2,165.3	$ 1,874.4
Insurance | Reinsurance Contracts [Axis]: LPT, deferred gain
Movement in net provision for losses and LAE for claims incurred:
Prior years		(13.2)
Insurance | Reinsurance Contracts [Axis]: LPT, offset post-LPT years
Movement in net provision for losses and LAE for claims incurred:
Prior years		$ (4.7)
Enstar
Net Losses and LAE payments for claims incurred:
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 770
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year								770
Enstar | Reinsurance Contracts [Axis]: LPT losses reinsured]
Net Losses and LAE payments for claims incurred:
Plus reinsurance recoverable on unpaid losses at the end of the year								3,120
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Plus reinsurance recoverable on unpaid losses at the end of the year								$ 3,120
Enstar | Reinsurance Contracts [Axis]: LPT net losses reinsured
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Event	$ 3,120

Reserves for Losses and Adju_12

Reserves for Losses and Adjustment Expenses - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Insurance [Abstract]
Provision for losses and LAE for claims incurred	$ (6.4)	$ (7.3)	$ 28.1	$ 45.1	$ (0.9)
Prior years	(6.4)	(7.3)	28.1	45.1	(0.9)
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	(6.4)	$ (7.3)	28.1	$ 45.1	$ (0.9)
Reinsurance
Insurance [Abstract]
Provision for losses and LAE for claims incurred	(2.1)
Prior years	(2.1)
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	(2.1)
Insurance
Insurance [Abstract]
Provision for losses and LAE for claims incurred	8.5		86.9
Prior years	8.5		86.9
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	8.5		$ 86.9
Insurance | Reinsurance Contracts [Axis]: LPT, deferred gain
Insurance [Abstract]
Provision for losses and LAE for claims incurred	13.2
Prior years	13.2
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	13.2
Insurance | Reinsurance Contracts [Axis]: LPT, offset post-LPT years
Insurance [Abstract]
Provision for losses and LAE for claims incurred	4.7
Prior years	4.7
Financial Guarantee Insurance Contracts, Premium Received over Contract Period [Line Items]
Prior years	$ 4.7

Reserves for Losses and Adju_13

Reserves for Losses and Adjustment Expenses - Reconciliation of Reinsurance Recoverables on Unpaid Losses (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 30, 2022
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance	$ 4,897.7	$ 3,298.1	$ 3,298.1
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance, Ending Balance			4,897.7	$ 3,298.1
Provision for losses and LAE for claims incurred	(6.4)	(7.3)	28.1	45.1	$ (0.9)
Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Provision for losses and LAE for claims incurred	(2.1)
Reinsurance Contracts [Axis]: LPT
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverables, premium paid and recognized						$ 1,840.1
Reinsurance Contracts [Axis]: Retroactive Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance	2,132	$ 838.1	838.1
Reinsurance recoverable for unpaid claims under retroactive reinsurance, beginning balance, Ending Balance	$ 1,877.3		$ 2,132	$ 838.1

Capital Structure - Summary o_3

Capital Structure - Summary of Authorized and Issued Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands				6 Months Ended	12 Months Ended
	Jun. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	May 02, 2013
Authorized share capital:
Number of ordinary shares				70,000,000	70,000,000	70,000,000
Number of preference shares				30,000,000	30,000,000	30,000,000
Ordinary Shares, authorized				$ 700	$ 700	$ 700
Preference Shares, authorized				45	45	45
Authorized share capital				$ 745	$ 745	$ 745
Issued share capital:
Ordinary shares, issued				60,395,839	60,395,839	60,395,839
Ordinary shares, value				$ 604	$ 604	$ 604
Total issued share capital				$ 636	$ 636	$ 636
Ordinary shares, par value				$ 0.01	$ 0.01	$ 0.01
Preference shares, par value				$ 0.0015144558	$ 0.0015144558
5.950% Preference Shares (AHL PRC)
Issued share capital:
Preference shares, issued				11,000,000	11,000,000	11,000,000	11,000,000
Preference shares, value				$ 17	$ 17	$ 17
Preferred Stock, Dividend Rate, Percentage	5.95%			5.95%	5.95%	5.95%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share							$ 25
5.625% Preference Shares (AHL PRD)
Issued share capital:
Preference shares, issued			10,000,000	10,000,000	10,000,000	10,000,000
Preference shares, value				$ 15	$ 15	$ 15
Preferred Stock, Dividend Rate, Percentage	5.625%		5.625%	5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share			$ 25	$ 25	$ 25	$ 25
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Issued share capital:
Preference shares, issued		10,000,000		10,000,000	10,000,000	10,000,000
Preference shares, value				$ 0	$ 0	$ 0
Preferred Stock, Dividend Rate, Percentage	5.625%	5.625%		5.625%	5.625%	5.625%
Preference shares, par value				$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Redemption price per share		$ 25		$ 25	$ 25	$ 25

Capital Structure - Summary o_4

Capital Structure - Summary of Authorized and Issued Share Capital (Details)(Phantom) - $ / shares	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 13, 2019	Sep. 20, 2016	May 02, 2013
Class of Stock [Line Items]
Ordinary shares, par value	$ 0.01	$ 0.01	$ 0.01
Preference shares, par value	0.0015144558	0.0015144558
5.950% Preference Shares (AHL PRC)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share						$ 25
5.625% Preference Shares (AHL PRD)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share	25	25	25		$ 25
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Class of Stock [Line Items]
Preference shares, par value	0.0015144558	0.0015144558	0.0015144558
Redemption price per share	$ 25	$ 25	$ 25	$ 25

Capital Structure - Additiona_2

Capital Structure - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands							6 Months Ended	12 Months Ended
	Jul. 01, 2023	Jun. 15, 2023	Mar. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	May 02, 2013	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2019
Class of Stock [Line Items]
Additional paid in capital								$ 1,514,700	$ 1,514,700
Preferred stock issuance cost							$ 21,500	21,500	21,500
Authorized share capital							$ 745	$ 745	$ 745
Number of ordinary shares							70,000,000	70,000,000	70,000,000
Ordinary shares, par value							$ 0.01	$ 0.01	$ 0.01
Number of preference shares							30,000,000	30,000,000	30,000,000
Preference shares, par value							$ 0.0015144558	$ 0.0015144558
Ordinary shares, issued							60,395,839	60,395,839	60,395,839
Preference shares liquidation preference, value				$ 250,000
5.950% Preference Shares (AHL PRC)
Class of Stock [Line Items]
Preferred stock issuance cost						$ 4,400
Preference shares, par value							$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued						11,000,000	11,000,000	11,000,000	11,000,000
Preference shares, rate		5.95%					5.95%	5.95%	5.95%
Redemption price per share						$ 25
Proceeds or share issuance						$ 270,600
Preference shares liquidation preference, value						$ 275,000
5.950% Preference Shares (AHL PRC) | Subsequent Event
Class of Stock [Line Items]
Preference shares, rate			5.95%
5.950% Preference Shares (AHL PRC) | LIBOR | Subsequent Event
Class of Stock [Line Items]
Preferred Stock Liquidation Preference Value, Fixed for Floating Rate	LIBOR
5.625% Preference Shares (AHL PRD)
Class of Stock [Line Items]
Preferred stock issuance cost					$ 8,700					$ 8,700
Preference shares, par value							$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued					10,000,000		10,000,000	10,000,000	10,000,000
Preference shares, rate		5.625%			5.625%		5.625%	5.625%	5.625%
Redemption price per share					$ 25		$ 25	$ 25	$ 25
Proceeds or share issuance					$ 241,300
Preference shares liquidation preference, value					$ 250,000					$ 250,000
5.625% Preference Shares (AHL PRD) | Subsequent Event
Class of Stock [Line Items]
Preference shares, rate			5.625%
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Class of Stock [Line Items]
Preferred stock issuance cost				$ 8,400
Preference shares, par value							$ 0.0015144558	$ 0.0015144558	$ 0.0015144558
Preference shares, issued				10,000,000			10,000,000	10,000,000	10,000,000
Preference shares, rate		5.625%		5.625%			5.625%	5.625%	5.625%
Redemption price per share				$ 25			$ 25	$ 25	$ 25
5.625% Preference Shares, rep by Dep Shares (AHL PRE) | Subsequent Event
Class of Stock [Line Items]
Preference shares, rate			5.625%
Additional paid-in capital | Preference shares
Class of Stock [Line Items]
Proceeds or share issuance				$ 241,600

Dividends - Summary of Declar_2

Dividends - Summary of Declared Dividends (Details) - USD ($) $ / shares in Units, $ in Millions								6 Months Ended	12 Months Ended
	Jul. 01, 2023	Jun. 15, 2023	Apr. 14, 2023	Apr. 01, 2023	Mar. 15, 2023	Aug. 13, 2019	Sep. 20, 2016	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 01, 2023
Dividends Payable [Line Items]
Payments of Ordinary Dividends								$ 20	$ 40
5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.625%				5.625%		5.625%	5.625%	5.625%
5.950% Preference Shares (AHL PRC)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.95%						5.95%	5.95%	5.95%
5.625% Preference Shares (AHL PRD)
Dividends Payable [Line Items]
Record Date		Jun. 15, 2023
Preferred Stock, Dividend Rate, Percentage		5.625%					5.625%	5.625%	5.625%	5.625%
Subsequent Event
Dividends Payable [Line Items]
Payments of Ordinary Dividends			$ 20
Subsequent Event | 5.625% Preference Shares, rep by Dep Shares (AHL PRE)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 351.56										$ 351.56
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Depositary share dividend	$ 0.35156										0.35156
Preferred Stock, Dividend Rate, Percentage					5.625%
Subsequent Event | 5.950% Preference Shares (AHL PRC)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 0.3719										0.3719
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Preferred Stock, Dividend Rate, Percentage					5.95%
Subsequent Event | 5.625% Preference Shares (AHL PRD)
Dividends Payable [Line Items]
Dividend, in usd per share	$ 0.3516										$ 0.3516
Payable Date	Jul. 01, 2023			Apr. 01, 2023
Record Date					Mar. 15, 2023
Preferred Stock, Dividend Rate, Percentage					5.625%

Related Party Transactions - _2

Related Party Transactions - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Related Party Transaction [Line Items]
Plus component of annual investment management fee	0.25	0.25
Annual fee cap	0.15	0.15
Privately-held Investments	$ 482.4	$ 533		$ 307.1
Other investments, at fair value (2)	213.4	221.3		151.3
Asset Management Arrangement
Related Party Transaction [Line Items]
Related party fees				(5.8)	$ (5.3)
Asset Management Arrangement | Investment Income
Related Party Transaction [Line Items]
Related party fees	(5.2)	(4.9)	$ (0.6)
Management Consulting Agreement
Related Party Transaction [Line Items]
Related party fees				(5)	$ (5)
Management Consulting Agreement | General, administrative and corporate expenses
Related Party Transaction [Line Items]
Related party fees	(2.5)	(5)	(2.5)
Apollo originating partnership | Gain (Loss) on Investments
Related Party Transaction [Line Items]
Related party fees	(0.4)	(1.5)	(0.2)
Beneficial owner
Related Party Transaction [Line Items]
Intercompany balance payable	2.2	2		0.6
Apollo real estate fund | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Other investments, at fair value (2)	22.9	25.3
Apollo originating partnership | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	42.7	44.8
Other investments, at fair value (2)	12.6	12.7
Apollo originating partnership, class A notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred	1.3	0.2	0.5
Apollo originating partnership, class A notes | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	28.6	30
Apollo originating partnership, class B notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred	0.7	0.2	$ 0.3
Apollo originating partnership, class B notes | Fair Value, Recurring [Member]
Related Party Transaction [Line Items]
Privately-held Investments	$ 14	$ 14.8
Apollo, Class A & B Notes | Privately-held investments
Related Party Transaction [Line Items]
Privately-held investment, losses incurred				$ 0
Maximum
Related Party Transaction [Line Items]
Percentage of consolidated group's net income due to Apollo Management	1%	1%
Fees due to Apollo Management	$ 5	$ 5

Commitments and Contingencies_5

Commitments and Contingencies - Schedule of Company's Restricted Assets (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Apr. 01, 2022	Sep. 30, 2021	Dec. 20, 2017
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	$ 266.5	$ 471.3	$ 539.8
Restricted assets, excluding illiquid assets	3,657.3	3,996.1	4,530.8
Other investments, at fair value (2)	213.4	221.3	151.3
Total restricted assets	$ 3,870.7	$ 4,217.4	$ 4,682.1
Total as percent of investable assets	52.60%	59.40%	59.70%
Securities and cash as collateral secured letters of credit	$ 266.5	$ 471.3	$ 539.8
Affiliated transactions
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	617	707.1	891.3
Third party
Fair Value, Separate Account Investment [Line Items]
Restricted Assets	2,773.8	2,817.7	3,099.7
Limited Partner | Real estate fund
Fair Value, Separate Account Investment [Line Items]
Restricted Assets				$ 10	$ 20	$ 100
Other investments, at fair value (2)	$ 213.4	$ 221.3	$ 151.3

Commitments and Contingencies_6

Commitments and Contingencies - Additional Information (Details) £ in Millions, SFr in Millions, $ in Millions, $ in Millions, $ in Millions, $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2023 GBP (£)	Jun. 30, 2023 CAD ($)	Jun. 30, 2023 AUD ($)	Jun. 30, 2023 CHF (SFr)	Jun. 30, 2023 SGD ($)	Dec. 31, 2022 GBP (£)	Dec. 31, 2022 CAD ($)	Dec. 31, 2022 AUD ($)	Dec. 31, 2022 CHF (SFr)	Dec. 31, 2022 SGD ($)	Apr. 01, 2022 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2021 CAD ($)	Dec. 31, 2021 AUD ($)	Dec. 31, 2021 CHF (SFr)	Dec. 31, 2021 SGD ($)	Sep. 30, 2021 USD ($)	Dec. 23, 2019 USD ($)	Dec. 20, 2017 USD ($)
Restricted Cash And Collateral [Line Items]
Restricted assets		$ 266.5	$ 471.3	$ 539.8
Other investments (equity method)		$ 213.4	$ 221.3	$ 151.3
Total as percent of investable assets		52.60%	59.40%	59.70%
Investment in the period		$ 0.4	$ 2	$ 3.2
Investable assets held by the Company		7,400	7,100	7,800
Investable assets held by insurance regulators		$ 551	$ 489.5	565.8
Minimum capital required | £					£ 0.4					£ 0.4						£ 0.4
Percentage of reinsurance liabilities		100%	100%		100%	100%	100%	100%	100%	100%	100%	100%	100%	100%
Reinsurance liabilities		$ 1,009.3	$ 1,166.4	1,470.5
Assets held-in-trust		1,167.8	1,389.5	1,581.9
Regulatory deposits		10.3	6.7	6.9
Deposit with states		6.7	6.5	6.4
MVI
Restricted Cash And Collateral [Line Items]
Investment in the period	$ 0.8	0	0.4	0.4
Multi-Line Insurer
Restricted Cash And Collateral [Line Items]
Other investments (equity method)																						$ 5
Investment in the period		0.4	1.6	2.5
Us Multi Beneficiary Trust Fund
Restricted Cash And Collateral [Line Items]
Minimum trust fund		20	20
Assets held-in-trust		383.2	509.2	519.7
Us Surplus Lines Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		141	215.1	216
Canadian Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		151.8	137.2			$ 200.9					$ 185.8						$ 196.8
Australian Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		102	124.7				$ 153.2					$ 183.9						$ 226.6
Swiss Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		10.6	10.2					SFr 9.5					SFr 9.4						SFr 8
Singapore Trust Fund
Restricted Cash And Collateral [Line Items]
Assets held-in-trust		$ 127.5	$ 130.3						$ 172.6					$ 174.7						$ 178
Bermuda
Restricted Cash And Collateral [Line Items]
Percentage of reinsurance liabilities		100%	100%		100%	100%	100%	100%	100%	100%	100%	100%	100%	100%
Reinsurance liabilities		$ 306.7	$ 380.3	450.4
Limited Partner | Real estate fund
Restricted Cash And Collateral [Line Items]
Restricted assets															$ 10						$ 20		$ 100
Other investments (equity method)		$ 213.4	$ 221.3	$ 151.3

Concentration of Credit Risk _3

Concentration of Credit Risk - Additional Information (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Concentration Risk [Line Items]
Less foreign exchange (gains)/losses	$ 4,658	$ 4,897.7	$ 5,006.5	$ 3,298.1	$ 3,195.2
Reinsurance Recoverables, Collateralized	0.560	0.579
Underwriting premiums receivables (net of allowance for expected credit losses of 2022: $25.0 — 2021: $30.2)	$ 1,676.8	$ 1,482.4		1,304.6
Due for settlement	5.9	18.3
Premium Receivable, Allowance for Credit Loss	$ 21.6	$ 25		30.2
Allowable holdings of a single issue or issuer, percentage	2%	2%
Reinsurance Recoverable, Allowance for Credit Loss	$ 3.3	$ 3.7		$ 3.3	$ 3.8
Munich Re
Concentration Risk [Line Items]
Concentration risk	0.092	0.097
Everest Re
Concentration Risk [Line Items]
Concentration risk	0.160	0.163
Lloyd's
Concentration Risk [Line Items]
Concentration risk	0.078	0.082
AA- or higher
Concentration Risk [Line Items]
Reinsurance Recoverables, Collateralized	0.435	0.420
AA- or lower
Concentration Risk [Line Items]
Reinsurance Recoverables, Collateralized	0.005	0.001

Reclassifications from Accumu_6

Reclassifications from Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income Reclassification (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from operations before income taxes	$ 255.1	$ 53.1	$ (27)	$ 35.1	$ (38)
Income tax (expense)/benefit	(36.2)	(4.7)	78.1	(5.3)	(18.4)
General, administrative and corporate expenses	(232.7)	(233.4)	(494.2)	(418)	(410.9)
Net income/(loss)	218.9	48.4	51.1	29.8	(56.4)
Net (loss)	218.9	48.4	51.1	29.8	$ (56.4)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income/(loss)	2.5	22	70.4	(26.6)
Available for sale securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Available for sale securities — gross realized (losses)	(0.4)	(2.3)	(3.9)	(24.8)
Realized losses on sale of securities and cash and cash equivalents	7.2	30.1	58.9	4.4
Income (loss) from operations before income taxes	6.8	27.8	55	(20.4)
Income tax (expense)/benefit	0	0	0	0
Net (loss)	6.8	27.8	55	(20.4)
Realized derivatives | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax (expense)/benefit	0	0.6	0	0
General, administrative and corporate expenses	(4.3)	(6.4)	15.4	(6.2)
Net income/(loss)	$ (4.3)	$ (5.8)	$ 15.4	$ (6.2)

Subsequent Events - Narrative_2

Subsequent Events - Narrative (Details) $ in Millions	1 Months Ended
	Jul. 31, 2023 USD ($)
Subsequent Event
Subsequent Event [Line Items]
Delayed draw term loan facility	$ 300