Argo Group International (ARGO-PA) 10-Q 6 May 22 2022 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2022	May 04, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	1-15259
Entity Registrant Name	ARGO GROUP INTERNATIONAL HOLDINGS, LTD.
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	98-0214719
Entity Address, Address Line One	90 Pitts Bay Road
Entity Address, City or Town	Pembroke
Entity Address, Postal Zip Code	HM08
Entity Address, Country	BM
City Area Code	441
Local Phone Number	296-5858
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		34,958,238
Entity Central Index Key	0001091748
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Shares
Document Information [Line Items]
Title of 12(b) Security	Common Stock, Par Value of $1.00 Per Share
Trading Symbol	ARGO
Security Exchange Name	NYSE
Guarantee of Argo Group U.S., Inc. 6.500% Senior Notes due 2042
Document Information [Line Items]
Title of 12(b) Security	6.500% Senior Notes Due 2042 issued by Argo Group U.S., Inc. and The Guarantee With Respects Thereto
Trading Symbol	ARGD
Security Exchange Name	NYSE
Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/1000th Interest in 7.00% Resettable Fixed Rate Preference Share, Series A, Par Value $1.00 Per Share
Trading Symbol	ARGOPrA
Security Exchange Name	NYSE

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Investments:
Fixed maturities available-for-sale, at fair value (cost: 2022 - $4,302.7, 2021 - $4,203.2; allowance for expected credit losses: 2022 - $2.9, 2021 - $2.5)	$ 4,143.9	$ 4,223.3
Equity securities, at fair value (cost: 2022 - $61.3; 2021 - $70.3)	54	56.3
Other investments (cost: 2022 - $452.4; 2021 - $387.0)	452.5	387.2
Short-term investments, at fair value (cost: 2022 - $420.6; 2021 - $655.4)	421.1	655.8
Total investments	5,071.5	5,322.6
Cash	154	146.1
Accrued investment income	22.1	20.9
Premiums receivable	649.3	648.6
Reinsurance recoverables	2,857.9	2,966.4
Goodwill	147.3	147.3
Intangible assets, net of accumulated amortization	17.3	17.3
Current income taxes receivable, net	0	7.3
Deferred tax asset, net	99.2	73.6
Deferred acquisition costs, net	174.6	168
Ceded unearned premiums	494.9	506.7
Operating lease right-of-use assets	60.8	81.4
Other assets	232.1	211.6
Total assets	9,981	10,317.8
Liabilities and Shareholders' Equity
Reserves for losses and loss adjustment expenses	5,648.1	5,595
Unearned premiums	1,386	1,466.8
Accrued underwriting expenses and other liabilities	167.4	166.6
Ceded reinsurance payable, net	577.9	724.4
Funds held	65.8	76.6
Senior unsecured fixed rate notes	140.4	140.3
Other indebtedness	57.3	57
Junior subordinated debentures	258.3	258.2
Operating lease liabilities	69	97.7
Total liabilities	8,370.2	8,582.6
Commitments and contingencies (Note 14)
Shareholders' equity:
Preferred shares and additional paid-in capital - $1.00 par, 30,000,000 shares authorized; 6,000 shares issued at March 31, 2022 and December 31, 2021, respectively; liquidation preference $25,000	144	144
Common shares - $1.00 par, 500,000,000 shares authorized; 46,260,520 and 46,192,867 shares issued at March 31, 2022 and December 31, 2021, respectively	46.3	46.2
Additional paid-in capital	1,388.5	1,386.4
Treasury shares (11,315,889 shares at March 31, 2022 and December 31, 2021, respectively)	(455.1)	(455.1)
Retained earnings	622	636.4
Accumulated other comprehensive income, net of taxes	(134.9)	(22.7)
Total shareholders' equity	1,610.8	1,735.2
Total liabilities and shareholders' equity	$ 9,981	$ 10,317.8

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Fixed maturities available-for-sale, at cost	$ 4,302.7	$ 4,203.2
Allowance for expected credit losses	2.9	2.5
Equity securities, cost	61.3	70.3
Other investments, cost	452.4	387
Short-term investments, cost	$ 420.6	$ 655.4
Preferred shares, par value (in dollars per share)	$ 1	$ 1
Preferred shares, shares authorized (in shares)	30,000,000	30,000,000
Preferred shares, shares issued (in shares)	6,000	6,000
Liquidation preference (in dollars per share)	$ 25,000	$ 25,000
Common shares, par value (in dollars per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	500,000,000	500,000,000
Common shares, shares issued (in shares)	46,260,520	46,192,867
Treasury shares (in shares)	11,315,889	11,315,889

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Premiums and other revenue:
Earned premiums	$ 480.6	$ 466.1
Net investment income	37.7	44.4
Net realized investment and other gains (losses):
Net realized investment and other losses	(40.2)	(1.3)
Change in fair value recognized	6.7	15.5
Change in allowance for credit losses on fixed maturity securities	(1)	(1.1)
Total net realized investment and other gains (losses)	(34.5)	13.1
Total revenue	483.8	523.6
Expenses:
Losses and loss adjustment expenses	283.6	307.6
Underwriting, acquisition and insurance expenses	172.9	176.4
Non-operating expenses	7.4	1.9
Interest expense	5.8	5.1
Fee and other (income) expense, net	(0.8)	0.1
Foreign currency exchange losses	2.9	1.3
Total expenses	471.8	492.4
Income before income taxes	12	31.2
Income tax provision	13	1.4
Net income (loss)	(1)	29.8
Dividends on preferred shares	2.6	2.6
Net Loss attributable to common shareholders, diluted	(3.6)	27.2
Net Loss attributable to common shareholders, basic	$ (3.6)	$ 27.2
Net income (loss) attributable to common shareholders per common share:
Basic (in dollars per share)	$ (0.11)	$ 0.78
Diluted (in dollars per share)	(0.11)	0.78
Cash dividend declared - common shares (in dollars per share)	$ 0.31	$ 0.31
Weighted average common shares:
Basic (in shares)	34,891,935	34,712,650
Diluted (in shares)	34,891,935	34,938,013

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (1)	$ 29.8
Other comprehensive income (loss):
Foreign currency translation adjustments	4.1	(0.9)
Reclassification adjustment for foreign currency translation included in net income	27.3	0
Unrealized losses on fixed maturity securities:
Losses arising during the year	(172)	(62.1)
Reclassification adjustment for losses (gains) included in net income	(5.4)	(4)
Other comprehensive income (loss) before tax	(146)	(67)
Unrealized gains (losses) on fixed maturity securities:
Losses arising during the year	(32.8)	(11.8)
Reclassification adjustment for (gains) losses included in net income	(1)	(0.8)
Income tax (benefit) provision related to other comprehensive income (loss)	(33.8)	(12.6)
Other comprehensive loss, net of tax	(112.2)	(54.4)
Comprehensive loss	$ (113.2)	$ (24.6)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Preferred Shares and Additional Paid-in Capital	Common Shares	Additional Paid-In Capital	Treasury Shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2020	$ 1,857.8	$ 144	$ 46	$ 1,380.2	$ (455.1)	$ 684.1	$ 58.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	29.8					29.8
Other comprehensive loss - Change in fair value of fixed maturities, net of taxes	(53.5)						(53.5)
Other comprehensive loss, net - Other	(0.9)						(0.9)
Activity under stock incentive plans	2.2		0.1	2.1
Retirement of common shares (tax payments on equity compensation)	(1.4)			(1.4)
Employee stock purchase plan	0.4			0.4
Dividends on preferred shares	(2.6)					(2.6)
Cash dividend declared - common shares	(10.8)					(10.8)
Ending Balance at Mar. 31, 2021	1,821	144	46.1	1,381.3	(455.1)	700.5	4.2
Beginning Balance at Dec. 31, 2021	1,735.2	144	46.2	1,386.4	(455.1)	636.4	(22.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1)					(1)
Other comprehensive loss - Change in fair value of fixed maturities, net of taxes	(143.6)						(143.6)
Other comprehensive loss, net - Other	31.4						31.4
Activity under stock incentive plans	2.8		0.1	2.7
Retirement of common shares (tax payments on equity compensation)	(1)			(1)
Employee stock purchase plan	0.4			0.4
Dividends on preferred shares	(2.6)					(2.6)
Cash dividend declared - common shares	(10.8)					(10.8)
Ending Balance at Mar. 31, 2022	$ 1,610.8	$ 144	$ 46.3	$ 1,388.5	$ (455.1)	$ 622	$ (134.9)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	Feb. 16, 2022	Feb. 12, 2021	Mar. 31, 2022	Mar. 31, 2021
Statement of Stockholders' Equity [Abstract]
Cash dividend declared - common shares (in dollars per share)	$ 0.31	$ 0.31	$ 0.31	$ 0.31

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows (used in) provided by operating activities:
Net income (loss)	$ (1)	$ 29.8
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Amortization and depreciation	5.9	2.9
Share-based payments expense	3.2	2.3
Deferred income tax benefit, net	9.3	0.3
Net realized investment (gains) losses	34.5	(13.1)
Undistributed earnings from alternative investment portfolio	(13.6)	(20.7)
Change in:
Accrued investment income	(1.2)	(0.6)
Receivables	43.9	242.5
Deferred acquisition costs	(6.5)	(6.5)
Ceded unearned premiums	(2.9)	(11.8)
Reserves for losses and loss adjustment expenses	101.4	(268.2)
Unearned premiums	(38.5)	(33.6)
Ceded reinsurance payable and funds held	(147.8)	158.2
Income taxes	3.2	1.3
Accrued underwriting expenses and other liabilities	11.5	6.4
Other, net	(29.3)	(19)
Cash (used in) provided by operating activities	(27.9)	70.2
Cash flows provided by (used in) investing activities:
Sales of fixed maturity investments	291.1	264
Maturities and mandatory calls of fixed maturity investments	144.3	195.9
Sales of equity securities	9	14.6
Sales of other investments	20.9	27.1
Purchases of fixed maturity investments	(597.4)	(617.6)
Purchases of equity securities	(1)	(0.5)
Purchases of other investments	(17.9)	(20.6)
Change in foreign regulatory deposits and voluntary pools	(8.6)	(9.1)
Change in mortgage loans	(46.5)	0
Change in short-term investments	234.1	59.7
Settlements of foreign currency exchange forward contracts	0	(1.7)
Proceeds from sale of Argo Seguros Brasil, net of cash transferred	22.7	0
Purchases of fixed assets, net	(0.7)	(7.7)
Other, net	0	45.9
Cash used in investing activities	50	(50)
Cash flows used in financing activities:
Activity under stock incentive plans	(1.1)	0.3
Payment of cash dividends to preferred shareholders	(2.6)	(2.6)
Payment of cash dividends to common shareholders	(10.8)	(10.8)
Cash used in financing activities	(14.5)	(13.1)
Effect of exchange rate changes on cash	0.3	0.8
Change in cash	7.9	7.9
Cash, beginning of year	146.1	148.8
Cash, end of period	$ 154	$ 156.7

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of Argo Group International Holdings, Ltd. and its subsidiaries (“Argo Group,” “we,” “us,” “our” or the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance products in the property and casualty market. The preparation of interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our consolidated financial statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; estimates of written and earned premiums; reinsurance premium receivable; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of goodwill and intangibles and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual financial statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K and Form 10-K/A for the year ended December 31, 2021 filed with the Securities and Exchange Commission ("SEC") (collectively, “2021 Form 10-K”). The interim financial information as of, and for, the three months ended, March 31, 2022 and 2021 is unaudited. However, in the opinion of management, the interim information includes all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the results presented for the interim periods. The operating results for the interim periods are not necessarily indicative of the results to be expected for the full year. All significant intercompany amounts have been eliminated in consolidation. Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation. Sale of Argo Seguros Brasil S.A. On February 15, 2022, we completed the sale of our Brazilian operations, Argo Seguros Brasil S.A. (“Argo Seguros”), to Spice Private Equity Ltd., an investment company focused on global private equity investments, for a purchase price of 160 million Brazilian Reais (approximately $30.5 million), subject to the terms and conditions set forth in the purchase agreement. Argo Seguros is one of the units within our International Operations reporting segment. As a result, we realized a loss on the sale of Argo Seguros of $28.5 million, which is included as a component of Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). This loss was primarily attributable to the realization of historical foreign currency translation, which was previously a component of accumulated other comprehensive income. We previously recognized a $6.3 million loss during 2021 as we adjusted the carrying value of Argo Seguros to its fair value.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting PronouncementsThe Company evaluated recently issued accounting pronouncements and determined none are material to our results of operations or financial position reported herein.

Investments

Investments	3 Months Ended
	Mar. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Included in Total investments in our Consolidated Balance Sheets at March 31, 2022 and December 31, 2021 is $71.2 million and $89.6 million, respectively, of assets managed on behalf of the trade capital providers, who are third-party participants that provide underwriting capital to the operations of Syndicates 1200 and 1910. Fixed Maturities The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: March 31, 2022 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 496.0 $ 0.4 $ 17.0 $ — $ 479.4 Foreign Governments 211.7 3.7 7.6 0.3 207.5 Obligations of states and political subdivisions 169.6 2.3 4.9 0.4 166.6 Corporate bonds 2,009.0 9.7 86.2 2.1 1,930.4 Commercial mortgage-backed securities 422.7 0.6 23.1 — 400.2 Residential mortgage-backed securities 455.4 1.9 26.5 — 430.8 Asset-backed securities 205.6 0.3 5.3 0.1 200.5 Collateralized loan obligations 332.7 0.6 4.8 — 328.5 Total fixed maturities $ 4,302.7 $ 19.5 $ 175.4 $ 2.9 $ 4,143.9 December 31, 2021 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 422.7 $ 5.5 $ 3.2 $ — $ 425.0 Foreign Governments 234.7 2.2 3.9 0.2 232.8 Obligations of states and political subdivisions 166.7 5.8 1.2 — 171.3 Corporate bonds 1,972.3 33.5 20.3 2.2 1,983.3 Commercial mortgage-backed securities 416.7 6.3 4.3 — 418.7 Residential mortgage-backed securities 480.7 7.5 5.7 — 482.5 Asset-backed securities 173.0 1.3 0.6 0.1 173.6 Collateralized loan obligations 336.4 1.3 1.6 — 336.1 Total fixed maturities $ 4,203.2 $ 63.4 $ 40.8 $ 2.5 $ 4,223.3 Contractual Maturity The amortized cost and fair values of fixed maturity investments as of March 31, 2022, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 229.3 $ 232.1 Due after one year through five years 1,849.4 1,795.6 Due after five years through ten years 719.4 673.7 Due after ten years 88.2 82.5 Structured securities 1,416.4 1,360.0 Total $ 4,302.7 $ 4,143.9 The actual maturities may differ from the contractual maturities because debtors may have the right to call or prepay obligations. Other Investments Details regarding the carrying value and unfunded investment commitments of other investments as of March 31, 2022 and December 31, 2021 were as follows: March 31, 2022 (in millions) Carrying Unfunded Investment Type Hedge funds $ 58.1 $ — Private equity 259.6 68.8 Overseas deposits 83.6 — Commercial Mortgage Loans 46.5 — Other 4.7 — Total other investments $ 452.5 $ 68.8 December 31, 2021 (in millions) Carrying Unfunded Investment Type Hedge funds $ 58.6 $ — Private equity 248.9 64.2 Overseas deposits 74.9 — Other 4.8 — Total other investments $ 387.2 $ 64.2 The following describes each investment type: • Hedge funds: Hedge funds include funds that primarily buy and sell stocks, including short sales, multi-strategy credit, relative value credit and distressed credit. • Private equity: Private equity includes buyout funds, real asset/infrastructure funds, credit special situations funds, mezzanine lending funds and direct investments and strategic non-controlling minority investments in private companies that are principally accounted for using the equity method of accounting. • Overseas deposits: Overseas deposits are principally invested in short-term sovereign fixed income and investment grade corporate securities and international stocks. • Commercial mortgage loans: Commercial mortgage loan investments are composed of participation interests in a portfolio of commercial mortgage loans. Loan collateral is diversified with regard to property type and geography. • Other: Other includes participation in investment pools. Unrealized Losses An aging of unrealized losses on our investments in fixed maturities is presented below: March 31, 2022 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 416.1 $ 12.8 $ 49.6 $ 4.2 $ 465.7 $ 17.0 Foreign Governments 150.2 6.7 25.4 0.9 175.6 7.6 Obligations of states and political subdivisions 78.7 4.7 3.0 0.2 81.7 4.9 Corporate bonds 1,275.0 62.9 219.6 23.3 1,494.6 86.2 Commercial mortgage-backed securities 296.8 17.8 41.7 5.3 338.5 23.1 Residential mortgage-backed securities 234.6 13.8 120.7 12.7 355.3 26.5 Asset-backed securities 135.9 4.7 7.0 0.6 142.9 5.3 Collateralized loan obligations 274.8 4.8 1.0 — 275.8 4.8 Total fixed maturities $ 2,862.1 $ 128.2 $ 468.0 $ 47.2 $ 3,330.1 $ 175.4 December 31, 2021 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 193.4 $ 2.6 $ 14.6 $ 0.6 $ 208.0 $ 3.2 Foreign Governments 152.4 3.3 2.6 0.6 155.0 3.9 Obligations of states and political subdivisions 46.0 0.8 0.1 0.4 46.1 1.2 Corporate bonds 854.3 18.3 41.7 2.0 896.0 20.3 Commercial mortgage-backed securities 198.8 4.1 6.5 0.2 205.3 4.3 Residential mortgage-backed securities 284.2 5.6 4.0 0.1 288.2 5.7 Asset-backed securities 62.6 0.6 — — 62.6 0.6 Collateralized loan obligations 176.1 1.6 0.5 — 176.6 1.6 Total fixed maturities $ 1,967.8 $ 36.9 $ 70.0 $ 3.9 $ 2,037.8 $ 40.8 We hold a total of 5,203 fixed maturity securities, of which 1,080 were in an unrealized loss position for less than one year and 208 were in an unrealized loss position for a period one year or greater as of March 31, 2022. Allowance for Credit Losses For fixed maturities with a decline in the fair value between the amortized cost due to credit-related factors, an allowance is established for the difference between the estimated recoverable value and amortized cost with a corresponding charge to Net realized investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss). The allowance is limited to the difference between amortized cost and fair value. The estimated recoverable value is the present value of cash flows expected to be collected, as determined by management. The difference between fair value and amortized cost that is not associated with credit-related factors is recognized in the Condensed Consolidated Statements of Comprehensive Income (Loss). Accrued interest is excluded from the measurement of the allowance for credit losses. When determining if a credit loss has been incurred, we may consider the historical performance of the security, available market information and security specific considerations such as the priority payment of the security. In addition, inputs used in our analysis include, but are not limited to, credit ratings and downgrades, delinquency rates, missed scheduled interest or principal payments, purchase yields, underlying asset performance, collateral types, modeled default rates, modeled severity rates, call/prepayment rates, expected cash flows, industry concentrations, and potential or filed bankruptcies or restructurings. We evaluate for credit losses each quarter. If we determine that all or a portion of a fixed maturity is uncollectible, the uncollectible amortized cost is written off with a corresponding reduction to the allowance for credit losses. If we collect cash flows that were previously written off, the recovery is recognized in realized investment gains. We also consider whether we intend to sell an available-for-sale security or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in Net realized investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss) based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security. The following table presents a roll-forward of the changes in allowance for credit losses on available-for-sale fixed maturities by industry category for the three months ending March 31, 2022 and 2021, respectively: (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2022 $ 0.2 $ — $ 2.2 $ 0.1 $ 2.5 Securities for which allowance was not previously recorded 0.1 — 0.4 — 0.5 Securities sold during the period — — (0.6) — (0.6) Additional net increases (decreases) in existing allowance — 0.4 0.1 — 0.5 Ending balance, March 31, 2022 $ 0.3 $ 0.4 $ 2.1 $ 0.1 $ 2.9 (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2021 $ 0.2 $ 0.1 $ 6.1 $ 0.2 $ 6.6 Securities for which allowance was not previously recorded — — 2.1 — 2.1 Securities sold during the period — — (0.4) — (0.4) Additional net increases (decreases) in existing allowance (0.1) (0.1) (0.7) (0.2) (1.1) Ending balance, March 31, 2021 $ 0.1 $ — $ 7.1 $ — $ 7.2 Total credit impairment (gains) losses included in Net realized investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss) was $1.0 million and $1.1 million for the three months ended March 31, 2022 and 2021, respectively. Investment Gains and Losses The following table presents our gross realized investment gains and losses: For the Three Months Ended (in millions) 2022 2021 Realized gains on fixed maturities and other Fixed maturities $ 11.2 $ 5.5 Other investments, including short-terms 1.5 6.0 12.7 11.5 Realized losses on fixed maturities and other Fixed maturities (16.6) (1.5) Other investments, including short-terms (6.8) (9.5) (23.4) (11.0) Net (losses) recognized on fixed maturities and other Credit losses on fixed maturities (1.0) (1.1) Other (1) (28.5) — (29.5) (1.1) Equity securities Net realized gains (losses) on equity securities (1.0) (1.8) Change in unrealized gains (losses) on equity securities held at the end of the period 6.7 15.5 Net realized gains (losses) on equity securities 5.7 13.7 Net realized investment and other gains (losses) before income taxes (34.5) 13.1 Income tax (benefit) provision (0.7) 2.6 Net realized investment and other gains (losses), net of income taxes $ (33.8) $ 10.5 (1) Refer to the sale of Argo Seguros in Note 1, “Basis of Presentation” for additional information. The cost of securities sold is based on the specific identification method. Changes in unrealized gains (losses) related to investments are summarized as follows: For the Three Months Ended (in millions) 2022 2021 Change in unrealized gains (losses) Fixed maturities $ (177.9) $ (65.7) Other and short-term investments 0.1 (0.4) Net unrealized investment gains (losses) before income taxes (177.8) (66.1) Income tax provision (benefit) (33.9) (12.6) Net unrealized investment gains (losses), net of income taxes $ (143.9) $ (53.5) Foreign Currency Exchange Forward Contracts We enter into foreign currency exchange forward contracts to manage operational currency exposure from our non-USD insurance operations, and gain exposure to a total return strategy which invests in multiple currencies. The currency forward contracts are carried at fair value in our Condensed Consolidated Balance Sheets in Other liabilities and Other assets at March 31, 2022 and December 31, 2021, respectively. The net realized gains and (losses) are included in Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). The fair value of our foreign currency exchange forward contracts as of March 31, 2022 and December 31, 2021 was as follows: (in millions) March 31, 2022 December 31, 2021 Operational currency exposure $ (8.5) $ (0.3) Asset manager investment exposure 0.8 (0.3) Total $ (7.7) $ (0.6) The following table represents our gross realized investment gains and losses on our foreign currency exchange forward contracts: For the Three Months Ended (in millions) 2022 2021 Realized gains Operational currency exposure $ 2.5 $ 3.9 Asset manager investment exposure 1.1 1.0 Total return strategy — 8.5 Gross realized investment gains 3.6 13.4 Realized losses Operational currency exposure (8.8) (9.2) Total return strategy — (7.5) Gross realized investment losses (8.8) (16.7) Net realized investment (losses) gains on foreign currency exchange forward contracts $ (5.2) $ (3.3) Regulatory Deposits, Pledged Securities and Letters of Credit We are required to maintain assets on deposit with various regulatory authorities to support our insurance and reinsurance operations. We maintain assets pledged as collateral in support of irrevocable letters of credit issued under the terms of certain reinsurance agreements for reported loss and loss expense reserves. The following table presents our components of restricted assets: (in millions) March 31, 2022 December 31, 2021 Securities on deposit for regulatory and other purposes $ 177.0 $ 195.6 Securities pledged as collateral for letters of credit and other 185.4 193.9 Securities and cash on deposit supporting Lloyd’s business (1) 290.9 296.8 Total restricted investments $ 653.3 $ 686.3 (1) Argo Group is required to maintain Funds at Lloyd’s (“FAL”) to support it business for Syndicate 1200 and Syndicate 1910. At March 31, 2022 the amount pledged for FAL was $290.9 million, of which $137.6 million was provided by Argo Re Ltd. Fair Value Measurements Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market. Market participants are buyers and sellers in the principal (or most advantageous) market that are independent, knowledgeable, able to transact for the asset or liability and willing to transfer the asset or liability. Valuation techniques consistent with the market approach, income approach and/or cost approach are used to measure fair value. The inputs of these valuation techniques are categorized into three levels. • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the reporting date. We define actively traded as a security that has traded in the past seven days. We receive one quote per instrument for Level 1 inputs. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. We receive one quote per instrument for Level 2 inputs. • Level 3 inputs are unobservable inputs. Unobservable inputs reflect our own judgments about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. We receive fair value prices from third-party pricing services and our outside investment managers. These prices are determined using observable market information such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2022 and December 31, 2021. A description of the valuation techniques we use to measure assets at fair value is as follows: Fixed Maturities (Available-for-Sale) Levels 1 and 2: • United States Treasury securities are typically valued using Level 1 inputs. For these securities, we obtain fair value measurements from third-party pricing services using quoted prices (unadjusted) in active markets at the reporting date. • United States Government agencies, non-U.S. Government securities, obligations of states and political subdivisions, credit securities and foreign denominated government and credit securities are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, yield curves, live trading levels, trade execution data, credit information and the security’s terms and conditions, among other things. • Asset and mortgage-backed securities and collateralized loan obligations are reported at fair value using Level 2 or Level 3 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. Fixed Maturities (Available-for-Sale) Levels 3: We own term loans that are valued using unobservable inputs. Equity Securities Level 1: Equity securities are principally reported at fair value using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Equity Securities Level 3: We own certain equity securities that are reported at fair value using Level 3 inputs. The valuation techniques for these securities include the following: • Fair value measurements for an investment in an equity fund obtained by applying final prices provided by the administrator of the fund, which is based upon certain estimates and assumptions. • Fair value measurements from brokers and independent valuation services, both based upon estimates, assumptions and other unobservable inputs. Other Investments Level 2: Foreign regulatory deposits are assets held in trust in jurisdictions where there is a legal and regulatory requirement to maintain funds locally in order to protect policyholders. Lloyd’s is the appointed investment manager for the funds. These assets are invested in short-term government securities, agency securities and corporate bonds and are valued using Level 2 inputs based upon values obtained from Lloyd’s. Short-term Investments: Short-term investments are principally reported at fair value using Level 1 inputs, with the exception of short-term corporate and governmental bonds reported at fair value using Level 2 inputs as described in the fixed maturities section above. Values for the investments categorized as Level 1 are obtained from various financial institutions as of the reporting date. Based on an analysis of the inputs, our financial assets measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 479.5 $ 472.2 $ 7.3 $ — Foreign Governments 207.5 — 207.5 — Obligations of states and political subdivisions 166.6 — 166.6 — Corporate bonds 1,930.3 — 1,915.3 15.0 Commercial mortgage-backed securities 400.2 — 400.2 — Residential mortgage-backed securities 430.8 — 430.8 — Asset-backed securities 200.5 — 179.3 21.2 Collateralized loan obligations 328.5 — 328.5 — Total fixed maturities 4,143.9 472.2 3,635.5 36.2 Equity securities 54.0 36.4 — 17.6 Other investments 84.0 — 84.0 — Short-term investments 421.1 419.9 1.2 — $ 4,703.0 $ 928.5 $ 3,720.7 $ 53.8 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 425.0 $ 417.4 $ 7.6 $ — Foreign Governments 232.8 — 232.8 — Obligations of states and political subdivisions 171.3 — 171.3 — Corporate bonds 1,983.3 — 1,980.5 2.8 Commercial mortgage-backed securities 418.7 — 418.7 — Residential mortgage-backed securities 482.5 — 482.5 — Asset-backed securities 173.6 — 173.6 — Collateralized loan obligations 336.1 — 336.1 — Total fixed maturities 4,223.3 417.4 3,803.1 2.8 Equity securities 56.3 41.6 — 14.7 Other investments 75.4 — 75.4 — Short-term investments 655.8 653.9 1.9 — $ 5,010.8 $ 1,112.9 $ 3,880.4 $ 17.5 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs The fair value measurements in the tables above do not equal Total investments on our Consolidated Balance Sheets as they exclude certain other investments that are accounted for under the equity-method of accounting. A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Unobservable Inputs (Level 3) (in millions) Credit Financial Equity Total Beginning balance, January 1, 2022 $ 2.8 $ 14.7 $ 17.5 Transfers into Level 3 34.7 0.1 34.8 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income (0.4) 1.8 1.4 Included in other comprehensive income 0.8 — 0.8 Purchases, issuances, sales, and settlements: Purchases — 1.0 1.0 Issuances — — — Sales (1.7) — (1.7) Settlements — — — Ending balance, March 31, 2022 $ 36.2 $ 17.6 $ 53.8 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2021 $ — $ — $ — (in millions) Credit Financial Equity Total Beginning balance, January 1, 2021 $ 7.0 $ 17.5 $ 24.5 Transfers into Level 3 — 1.0 1.0 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income — 4.2 4.2 Included in other comprehensive loss (0.8) — (0.8) Purchases, issuances, sales, and settlements: Purchases 0.1 1.2 1.3 Issuances — — — Sales (3.5) (10.6) (14.1) Settlements — — — Ending balance, December 31, 2021 $ 2.8 $ 13.3 $ 16.1 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2020 $ — $ — $ — At March 31, 2022 and December 31, 2021, we did not have any financial assets or financial liabilities measured at fair value on a nonrecurring basis or any financial liabilities on a recurring basis.

Allowance for Credit Losses

Allowance for Credit Losses	3 Months Ended
	Mar. 31, 2022
Credit Loss [Abstract]
Allowance for Credit Losses	Allowance for Credit Losses Premiums receivable The following table represents the balances of premiums receivable, net of allowance for expected credit losses, at March 31, 2022 and January 1, 2022, and the changes in the allowance for expected credit losses for the three months ended March 31, 2022. (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Balance, January 1, 2022 $ 648.6 $ 5.7 Current period change for estimated uncollectible premiums (0.4) Write-offs of uncollectible premiums receivable — Balance, March 31, 2022 $ 649.3 $ 5.3 Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2022 and January 1, 2022, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2022. (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2022 $ 2,966.4 $ 3.8 Current period change for estimated uncollectible reinsurance — Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2022 $ 2,857.9 $ 3.8 We primarily utilize A.M. Best credit ratings when determining the allowance, and adjust as needed based on our historical experience with the reinsurers. A portion of our reinsurance recoverables are collateralized by letters of credit, funds held or trust agreements.

Reserves for Losses and Loss Ad

Reserves for Losses and Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 2022
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	Reserves for Losses and Loss Adjustment Expenses The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): For the Three Months Ended (in millions) 2022 2021 Net reserves beginning of the year $ 3,123.2 $ 2,906.1 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 280.2 306.6 Prior accident years 3.4 1.0 Losses and LAE incurred during calendar year, net of reinsurance 283.6 307.6 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 19.0 33.0 Prior accident years 266.1 230.3 Losses and LAE payments made during current calendar year, net of reinsurance: 285.1 263.3 Divestitures (1) (31.0) — Net reserve ceded - reinsurance to close transaction for years of account 2017 and prior (2) — 207.8 Change in participation interest (3) 48.0 19.8 Foreign exchange adjustments (0.4) (0.8) Net reserves - end of period 3,138.3 2,761.6 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,509.8 2,373.7 Gross reserves - end of period $ 5,648.1 $ 5,135.3 (1) Refer to the sale of Argo Seguros in Note 1, “Basis of Presentation” for additional information. (2) Amount represents reserves ceded under the reinsurance to close transaction with RiverStone for Lloyd’s years of account 2017 and prior, effective January 1, 2021. (3) Amount represents the change in reserves due to changing our participation in Syndicates 1200 and 1910. Reserves for losses and LAE represent the estimated indemnity cost and related adjustment expenses necessary to investigate and settle claims. Such estimates are based upon individual case estimates for reported claims, estimates from ceding companies for reinsurance assumed and actuarial estimates for losses that have been incurred but not yet reported to the insurer. Any change in probable ultimate liabilities is reflected in current operating results. The impact from the (favorable) unfavorable development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: For the Three Months Ended (in millions) 2022 2021 U.S. Operations $ 5.0 $ (0.4) International Operations (3.0) — Run-off Lines 1.4 1.4 Total (favorable) unfavorable prior-year development $ 3.4 $ 1.0 The following describes the primary factors behind each segment’s prior accident year reserve development for the three months ended March 31, 2022 and 2021: Three months ended March 31, 2022: • U.S. Operations : Unfavorable development primarily related to liability lines, including the impact of large losses, partially offset by favorable development in specialty lines. • International Operations : Favorable development primarily related to catastrophe losses and Europe liability losses partially offset by unfavorable development in liability and professional losses from our Bermuda insurance operations. • Run-off Lines: Unfavorable loss reserve development on prior accident years in other run-off lines. Three months ended March 31, 2021: • U.S. Operations : Favorable development primarily in specialty lines, partially offset by unfavorable development in liability and professional lines. • International Operations : Unfavorable development primarily related to a one-time accounting adjustment and large claim movements in Argo Insurance Bermuda, partially offset by favorable development in property lines, including losses associated with prior year catastrophe losses. • Run-off Lines: Unfavorable loss reserve development on prior accident years in risk management workers compensation, other run-off lines and an individual environmental loss. In the opinion of management, our reserves represent the best estimate of our ultimate liabilities, based on currently known facts, current law, current technology and reasonable assumptions where facts are not known. Due to the significant uncertainties and related management judgments, there can be no assurance that future favorable or unfavorable loss development, which may be material, will not occur.

Disclosures about Fair Value of

Disclosures about Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Disclosures about Fair Value of Financial Instruments	Disclosures About Fair Value of Financial Instruments Cash. The carrying amount approximates fair value. Investment securities and short-term investments. See Note 3, “Investments,” for additional information. Premiums receivable and reinsurance recoverables on paid losses. The carrying value of current receivables and reinsurance recoverables on paid losses approximates fair value. Debt. At March 31, 2022 and December 31, 2021, the fair value of our debt instruments is determined using both Level 1 and Level 2 inputs, as previously defined in Note 3, “Investments.” We receive fair value prices from third-party pricing services for our financial instruments as well as for similar financial instruments. These prices are determined using observable market information such as publicly traded quoted prices, and trading prices for similar financial instruments actively being traded in the current market. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2022 and December 31, 2021. A description of the valuation techniques we use to measure these liabilities at fair value is as follows: Senior Unsecured Fixed Rate Notes Level 1: • Our senior unsecured fixed rate notes are valued using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Junior Subordinated Debentures and Floating Rate Loan Stock Level 2: • Our trust preferred debentures, subordinated debentures and floating rate loan stock are typically valued using Level 2 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices for similar securities being traded in active markets at the reporting date, as our specific debt instruments are more infrequently traded. A summary of our financial instruments whose carrying value did not equal fair value is shown below: March 31, 2022 December 31, 2021 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 172.7 $ 173.2 $ 172.7 $ 172.9 Subordinated debentures 85.6 92.1 85.5 91.9 Total junior subordinated debentures 258.3 265.3 258.2 264.8 Senior unsecured fixed rate notes 140.4 144.1 140.3 148.4 Floating rate loan stock 57.3 57.4 57.0 57.1 $ 456.0 $ 466.8 $ 455.5 $ 470.3 Based on an analysis of the inputs, our financial instruments measured at fair value for disclosure purposes have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, 2022 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 173.2 $ — $ 173.2 $ — Subordinated debentures 92.1 — 92.1 — Total junior subordinated debentures 265.3 — 265.3 — Senior unsecured fixed rate notes 144.1 144.1 — — Floating rate loan stock 57.4 — 57.4 — $ 466.8 $ 144.1 $ 322.7 $ — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2021 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 172.9 $ — $ 172.9 $ — Subordinated debentures 91.9 — 91.9 — Total junior subordinated debentures 264.8 — 264.8 — Senior unsecured fixed rate notes 148.4 148.4 — — Floating rate loan stock 57.1 — 57.1 — $ 470.3 $ 148.4 $ 321.9 $ — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity On February 16, 2022, our Board of Directors declared a quarterly cash dividend in the amount of $0.31 on each common share outstanding. On March 15, 2022, we paid $10.8 million to our shareholders of record on February 28, 2022. On February 16, 2022, our Board of Directors declared a quarterly cash dividend in the amount of $437.500 per share on our 7.00% Resettable Fixed Rate Preference Shares, Series A, par value of $1.00 per share, with a liquidation preference of $25,000 per share (the “Series A Preference Shares”). Holders of depositary shares, each representing a 1/1,000th interest in a Series A Preference Share (the “Depositary Shares”), received $0.437500 per Depositary Share. On March 15, 2022, we paid $2.6 million to our shareholders of record of Series A Preference Shares on February 28, 2022. On February 12, 2021, our Board of Directors declared a quarterly cash dividend in the amount of $0.31 on each common share outstanding. On March 12, 2021, we paid $10.8 million to our shareholders of record on February 26, 2021. On February 12, 2021, our Board of Directors declared a quarterly cash dividend in the amount of $437.50 per share on our 7.00% Resettable Fixed Rate Preference Shares, Series A, par value of $1.00 per share, with a liquidation preference of $25,000 per share (the “Series A Preference Shares”). Holders of depositary shares, each representing a 1/1,000th interest in a Series A Preference Share (the “Depositary Shares”), received $0.43750 per Depositary Share. On March 15, 2021, we paid $2.6 million to our shareholders of record of Series A Preference Shares on February 28, 2021. On May 3, 2016, our Board of Directors authorized the repurchase of up to $150.0 million of our common shares (“2016 Repurchase Authorization”). The 2016 Repurchase Authorization supersedes all previous repurchase authorizations. As of March 31, 2022, availability under the 2016 Repurchase Authorization for future repurchases of our common shares was $53.3 million. We did not repurchase any common shares for the three months ended March 31, 2022.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) A summary of changes in accumulated other comprehensive (loss) income, net of taxes (where applicable) by component for the three months ended March 31, 2022 and 2021 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2022 $ (35.3) $ 19.7 $ (7.1) $ (22.7) Other comprehensive income (loss) before reclassifications 4.1 (139.2) — (135.1) Amounts reclassified from accumulated other comprehensive loss 27.3 (4.4) — 22.9 Net current-period other comprehensive income (loss) 31.4 (143.6) — (112.2) Balance, March 31, 2022 $ (3.9) $ (123.9) $ (7.1) $ (134.9) (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2021 $ (37.9) $ 105.1 $ (8.6) $ 58.6 Other comprehensive loss before reclassifications (0.9) (50.3) — (51.2) Amounts reclassified from accumulated other comprehensive loss — (3.2) — (3.2) Net current-period other comprehensive loss (0.9) (53.5) — (54.4) Balance, March 31, 2021 $ (38.8) $ 51.6 $ (8.6) $ 4.2 The amounts reclassified from accumulated other comprehensive income (loss) shown in the above table have been included in the following captions in our Condensed Consolidated Statements of Income (Loss): For the Three Months Ended (in millions) 2022 2021 Unrealized gains and losses on securities: Net realized investment gains $ (5.4) $ (4.0) Provision for income taxes 1.0 0.8 Foreign currency translation adjustments: Net realized investment and other gains (losses) 27.3 — Total, net of taxes $ 22.9 $ (3.2) Income tax effects are released from accumulated other comprehensive income (loss) for unrealized gains or losses when the gains or losses are realized, and are taxed at the statutory rate based on jurisdiction of the underlying transaction.

Net Income (Loss) Per Common Sh

Net Income (Loss) Per Common Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share	Net Income (Loss) Per Common Share The following table presents the calculation of net income (loss) per common share on a basic and diluted basis: For the Three Months Ended (in millions, except number of shares and per share amounts) 2022 2021 Net income (loss) $ (1.0) $ 29.8 Less: Preferred share dividends 2.6 2.6 Net income (loss) attributable to common shareholders (3.6) 27.2 Weighted average common shares outstanding - basic 34,891,935 34,712,650 Effect of dilutive securities: Equity compensation awards — 225,363 Weighted average common shares outstanding - diluted 34,891,935 34,938,013 Net income (loss) per common share: Basic $ (0.11) $ 0.78 Diluted $ (0.11) $ 0.78 Excluded from the weighted average common shares outstanding calculation at March 31, 2022 and 2021 are 11,315,889 shares, which are held as treasury shares. The shares are excluded as of their repurchase date. For the three months ended March 31, 2022, 173,541 potentially dilutive securities were not included in the calculation of diluted net income per common share as these instruments were anti-dilutive due to the net loss attributable to common shareholders incurred for the period then ended. For the three months ended March 31, 2021, there were no equity compensation awards with an anti-dilutive effect.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2022
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Interest paid and income taxes paid (recovered) were as follows: For the Three Months Ended (in millions) 2022 2021 Senior unsecured fixed rate notes $ 2.3 $ 2.3 Junior subordinated debentures 2.5 2.5 Other indebtedness 0.8 0.8 Total interest paid $ 5.6 $ 5.6 Income taxes paid $ 0.3 $ 0.9 Income taxes recovered (0.2) (0.1) Income taxes paid, net $ 0.1 $ 0.8

Share-based Compensation

Share-based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Share-based Compensation	Share-based Compensation Argo Group’s 2019 Omnibus Incentive Plan In May 2019, our shareholders approved the 2019 Omnibus Incentive Plan (the “2019 Plan”), which provides equity-based and cash-based incentives to key employees and non-employee directors. The intent of the 2019 Plan is to encourage and provide for the acquisition of an ownership interest in Argo Group, enabling us to attract and retain qualified and competent persons to serve as members of our management team and Board of Directors. The 2019 Plan authorizes 1,885,000 common shares to be granted as equity-based awards. No further grants will be made under any prior plan; however, any awards under a prior plan that are outstanding as of the effective date shall remain subject to the terms and conditions of, and be governed by, such prior plan. Awards granted under the 2019 Plan may be in the form of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards, other stock-based awards or other cash-based awards. Awards may be granted either alone, in addition to or in tandem with other awards authorized under the 2019 Plan. Awards that are settled in stock will count as one share for the purposes of reducing the share reserve under the 2019 Plan. Shares issued under this plan may be shares that are authorized and unissued or shares that we have reacquired, including shares purchased on the open market. Stock options and stock appreciation rights are required to have an exercise price that is not less than the fair market value on the date of grant. The term of these awards is not to exceed ten years. Restricted Shares A summary of non-vested restricted share activity as of March 31, 2022 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2022 278,430 $ 49.57 Granted 240,677 41.00 Reclassed from performance shares 14,373 32.61 Vested and issued (83,101) 46.32 Expired or forfeited (13,379) 48.72 Outstanding at March 31, 2022 437,000 $ 44.58 The restricted shares vest over one Underwriting, acquisition and insurance expenses in the accompanying Condensed Consolidated Statements of Income (Loss). As of March 31, 2022, there was $18.0 million of total unrecognized compensation cost related to restricted share compensation arrangements granted by Argo Group. Performance Shares We have issued to certain key employees non-vested restricted stock awards whose vesting is subject to the achievement of certain performance measures. The non-vested performance share awards vest over three A summary of non-vested performance share activity as of March 31, 2022 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2022 200,564 $ 47.52 Granted 125,074 41.00 Reclassed to restricted shares (14,373) 32.61 Vested and issued (1,831) 68.27 Expired or forfeited (17,398) 59.03 Outstanding at March 31, 2022 292,036 $ 44.64 Expense recognized under this plan for the performance shares was $0.5 million and $0.7 million for the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, there was $8.5 million of total unrecognized compensation cost related to performance share compensation arrangements granted by Argo Group.

Underwriting, Acquisition and I

Underwriting, Acquisition and Insurance Expenses	3 Months Ended
	Mar. 31, 2022
Underwriting, Acquisition and Insurance Expenses [Abstract]
Underwriting, Acquisition and Insurance Expenses	Underwriting, Acquisition and Insurance Expenses Underwriting, acquisition and insurance expenses were as follows: For the Three Months Ended (in millions) 2022 2021 Commissions $ 77.9 $ 76.5 Other underwriting and insurance expenses 103.2 106.6 Total underwriting, acquisition and insurance expenses before deferral 181.1 183.1 Net deferral of policy acquisition costs (8.2) (6.7) Total underwriting, acquisition and insurance expenses $ 172.9 $ 176.4

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are incorporated under the laws of Bermuda and, under current Bermuda law, are not obligated to pay any taxes in Bermuda based upon income or capital gains. We have received an undertaking from the Supervisor of Insurance in Bermuda pursuant to the provisions of the Exempted Undertakings Tax Protection Amendment Act, 2011, which exempts us from any Bermuda taxes computed on profits, income or any capital asset, gain or appreciation or any tax in the nature of estate, duty or inheritance tax, at least until the year 2035. We do not consider ourselves to be engaged in a trade or business in the U.S. or the U.K. and, accordingly, do not expect to be subject to direct U.S. or U.K. income taxation. We have subsidiaries based in the U.K. that are subject to the tax laws of that country. Under current law, these subsidiaries are taxed at the applicable corporate tax rates. Certain of the U.K. subsidiaries are deemed to be engaged in business in the U.S., and therefore, are subject to U.S. corporate tax in respect of a proportion of their U.S. underwriting business only. Relief is available against the U.K. tax liabilities in respect of overseas taxes paid that arise from the underwriting business. Our U.K. subsidiaries file separate U.K. income tax returns. We have subsidiaries based in the U.S. that are subject to U.S. tax laws. Under current law, these subsidiaries are taxed at the applicable corporate tax rates. Our U.S. subsidiaries generally file a consolidated U.S. federal income tax return. We also have operations in Brazil, France, Ireland, Italy, Malta, and Switzerland, which also are subject to income taxes imposed by the jurisdiction in which they operate. During the period ending March 31, 2022, our operations in Brazil were divested. We also have operations in Barbados and the United Arab Emirates, which are not subject to income tax under the laws of those countries. On June 10, 2021, U.K. tax legislation referred to as Finance Act 2021 received Royal Assent and was enacted. The effects of changes in tax laws and tax rates are recognized in the period of enactment. Accordingly, we recorded the impacts of Finance Act 2021 in our June 30, 2021 consolidated financial statements which primarily includes the remeasurement of our deferred tax assets and liabilities for the increased U.K. federal tax rate from 19% to 25% beginning on April 1, 2023. Our expected income tax provision computed on pre-tax income (loss) at the weighted average tax rate has been calculated as the sum of the pre-tax income (loss) in each jurisdiction multiplied by that jurisdiction’s applicable statutory tax rate. For the three months ended March 31, 2022 and 2021, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: For the Three Months Ended March 31, 2022 2021 (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ (0.2) — % $ 5.0 — % United States 38.8 21.9 % 41.3 15.7 % United Kingdom 5.0 80.8 % (18.3) 28.1 % Brazil (0.1) (422.4) % 1.6 — % United Arab Emirates 0.6 — % 0.3 — % Ireland (33.3) — % (0.1) — % Italy 0.1 138.1 % 0.9 — % Malta 1.1 — % 0.5 — % Pre-tax income $ 12.0 109.7 % $ 31.2 4.3 % Our effective tax rate may vary significantly from period to period depending on the jurisdiction generating the pre-tax income (loss) and its corresponding statutory tax rate. The geographic distribution of pre-tax income (loss) can fluctuate significantly between periods given the inherit nature of our business. A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate is as follows: For the Three Months Ended (in millions) 2022 2021 Income tax provision at expected rate $ 9.4 $ 6.3 Tax effect of: Nontaxable investment income (0.1) (0.2) Foreign exchange adjustments 0.1 (0.2) Sale of Brazil Operations 1.6 — Change in uncertain tax position liability 0.1 (2.4) Change in valuation allowance (1.8) (0.8) Impact of change in tax rate related to Finance Act 2021 0.5 — Lease termination 2.0 — Other 1.2 (1.3) Income tax provision $ 13.0 $ 1.4 Our gross deferred tax assets are supported by taxes paid in previous periods, reversal of taxable temporary differences and recognition of future taxable income. Management regularly evaluates the recoverability of the deferred tax assets and makes any necessary adjustments to them based upon any changes in management’s expectations of future taxable income. Realization of deferred tax assets is dependent upon our generation of future taxable income sufficient to recover tax benefits that cannot be recovered from taxes paid in the carryback period, generally for our U.S. property and casualty insurers two years for net operating losses and for all our U.S. subsidiaries three years for capital losses. If a company determines that any of its deferred tax assets will not result in future tax benefits, a valuation allowance must be established for the portion of these assets that are not expected to be realized. For the three months ended March 31, 2022, the net change in valuation allowance for deferred tax assets decreased $1.8 million relating to the following: Internal Revenue Code Section 382 limited net operating loss carryforwards within the United States, cumulative losses incurred since inception, and valuation allowances acquired through or related to acquisitions or disposals. Based upon a review of our available evidence, both positive and negative discussed above, our management concluded that it is more-likely-than-not that the other deferred tax assets will be realized. For any uncertain tax positions not meeting the “more-likely-than-not” recognition threshold, accounting standards require recognition, measurement and disclosure in a company’s financial statements. For the three months ended March 31, 2022, the uncertain tax positions liability increased in the amount of $0.1 million. A net increase of interest in the amount of $0.1 million has been recorded in the line item Interest expense in our Consolidated Statements of Income (Loss) for the three months ended March 31, 2022. Our U.S. subsidiaries are no longer subject to U.S. federal and state income tax examinations by tax authorities for years before 2018. Our U.K. subsidiaries are no longer subject to U.K. income tax examinations by Her Majesty’s Revenue and Customs for years before 2020. Numerous foreign jurisdictions in which we operate have provided or proposed income-tax relief in response to the COVID-19 pandemic. The Company does not anticipate any of the recent legislative initiatives to have a material impact on its financial statements and will continue to analyze these initiatives in response to the COVID-19 pandemic.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Argo Group’s subsidiaries are parties to legal actions incidental to their business. Based on the opinion of legal counsel, management believes that the resolution of these matters will not materially affect our financial condition or results of operations. We have contractual commitments to invest up to $68.8 million related to our limited partnership investments at March 31, 2022, as further disclosed in Note 3, “Investments.” These commitments will be funded as required by the partnership agreements which can be called to be fulfilled at any time, not to exceed twelve years.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2022
Segment Reporting [Abstract]
Segment Information	Segment Information We are primarily engaged in underwriting property and casualty insurance. We have two ongoing reporting segments: U.S. Operations and International Operations. Additionally, we have Run-off Lines for certain products that we no longer underwrite. We consider many factors, including the nature of each segment’s insurance and reinsurance products, production sources, distribution strategies and the regulatory environment, in determining how to aggregate reporting segments. In evaluating the operating performance of our segments, we focus on core underwriting and investing results before the consideration of realized gains or losses from investments. Realized investment gains are reported as a component of the Corporate and Other segment, as decisions regarding the acquisition and disposal of securities reside with the corporate investment function and are not under the control of the individual business segments. Identifiable assets by segment are those assets used in the operation of each segment. Revenue and income (loss) before income taxes for each segment were as follows: For the Three Months Ended (in millions) 2022 2021 Revenue: Earned premiums U.S. Operations $ 336.4 $ 314.4 International Operations 144.2 151.5 Run-off Lines — 0.2 Total earned premiums 480.6 466.1 Net investment income U.S. Operations 25.6 28.8 International Operations 11.4 12.0 Run-off Lines 0.7 0.8 Corporate and Other — 2.8 Total net investment income 37.7 44.4 Net realized investment and other gains (losses) (34.5) 13.1 Total revenue $ 483.8 $ 523.6 For the Three Months Ended (in millions) 2022 2021 Income (loss) before income taxes U.S. Operations $ 43.9 $ 36.6 International Operations 22.7 (11.8) Run-off Lines (1.0) 0.6 Total segment income (loss) before income taxes 65.6 25.4 Corporate and Other (16.2) (6.0) Net realized investment and other gains (losses) (34.5) 13.1 Foreign currency exchange losses (2.9) (1.3) Total income (loss) before income taxes $ 12.0 $ 31.2 The table below presents earned premiums by geographic location for the three months ended March 31, 2022 and 2021. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. For the Three Months Ended (in millions) 2022 2021 United States $ 336.4 $ 312.8 United Kingdom 127.1 99.0 Bermuda 6.4 25.1 Malta 2.3 14.0 All other jurisdictions 8.4 15.2 Total earned premiums $ 480.6 $ 466.1 The following table represents identifiable assets: (in millions) March 31, 2022 December 31, 2021 U.S. Operations $ 5,716.2 $ 5,800.1 International Operations 3,780.9 3,932.3 Run-off Lines 305.3 314.7 Corporate and Other 178.6 270.7 Total $ 9,981.0 $ 10,317.8 Included in total assets at March 31, 2022 and December 31, 2021 are $247.0 million and $825.9 million, respectively, in assets associated with trade capital providers.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On April 28, 2022, the Company announced that its Board of Directors has initiated an exploration of strategic alternatives. As part of this process, the Board of Directors will consider a wide range of options for the Company including, among other things, a potential sale, merger or other strategic transaction. There can be no assurance that this process will result in the Company pursuing a particular transaction or other strategic outcome. The Company has not set a timetable for completion of this process, and it does not intend to disclose further developments unless and until it determines that further disclosure is appropriate or necessary. Additionally, in April 2022, the Company reached agreement on a loss portfolio transfer (“LPT”) transaction for Syndicate 1200's reserves for the 2018 and 2019 Years of Account.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of Argo Group International Holdings, Ltd. and its subsidiaries (“Argo Group,” “we,” “us,” “our” or the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance products in the property and casualty market. The preparation of interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our consolidated financial statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; estimates of written and earned premiums; reinsurance premium receivable; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of goodwill and intangibles and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual financial statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K and Form 10-K/A for the year ended December 31, 2021 filed with the Securities and Exchange Commission ("SEC") (collectively, “2021 Form 10-K”).
Reclassification	Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation.
Fair Value Measurement	Fair Value Measurements Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market. Market participants are buyers and sellers in the principal (or most advantageous) market that are independent, knowledgeable, able to transact for the asset or liability and willing to transfer the asset or liability. Valuation techniques consistent with the market approach, income approach and/or cost approach are used to measure fair value. The inputs of these valuation techniques are categorized into three levels. • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the reporting date. We define actively traded as a security that has traded in the past seven days. We receive one quote per instrument for Level 1 inputs. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. We receive one quote per instrument for Level 2 inputs. • Level 3 inputs are unobservable inputs. Unobservable inputs reflect our own judgments about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. We receive fair value prices from third-party pricing services and our outside investment managers. These prices are determined using observable market information such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2022 and December 31, 2021. A description of the valuation techniques we use to measure assets at fair value is as follows: Fixed Maturities (Available-for-Sale) Levels 1 and 2: • United States Treasury securities are typically valued using Level 1 inputs. For these securities, we obtain fair value measurements from third-party pricing services using quoted prices (unadjusted) in active markets at the reporting date. • United States Government agencies, non-U.S. Government securities, obligations of states and political subdivisions, credit securities and foreign denominated government and credit securities are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, yield curves, live trading levels, trade execution data, credit information and the security’s terms and conditions, among other things. • Asset and mortgage-backed securities and collateralized loan obligations are reported at fair value using Level 2 or Level 3 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. Fixed Maturities (Available-for-Sale) Levels 3: We own term loans that are valued using unobservable inputs. Equity Securities Level 1: Equity securities are principally reported at fair value using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Equity Securities Level 3: We own certain equity securities that are reported at fair value using Level 3 inputs. The valuation techniques for these securities include the following: • Fair value measurements for an investment in an equity fund obtained by applying final prices provided by the administrator of the fund, which is based upon certain estimates and assumptions. • Fair value measurements from brokers and independent valuation services, both based upon estimates, assumptions and other unobservable inputs. Other Investments Level 2: Foreign regulatory deposits are assets held in trust in jurisdictions where there is a legal and regulatory requirement to maintain funds locally in order to protect policyholders. Lloyd’s is the appointed investment manager for the funds. These assets are invested in short-term government securities, agency securities and corporate bonds and are valued using Level 2 inputs based upon values obtained from Lloyd’s. Short-term Investments: Short-term investments are principally reported at fair value using Level 1 inputs, with the exception of short-term corporate and governmental bonds reported at fair value using Level 2 inputs as described in the fixed maturities section above. Values for the investments categorized as Level 1 are obtained from various financial institutions as of the reporting date.
Allowance for Credit Losses	Allowance for Credit Losses For fixed maturities with a decline in the fair value between the amortized cost due to credit-related factors, an allowance is established for the difference between the estimated recoverable value and amortized cost with a corresponding charge to Net realized investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss). The allowance is limited to the difference between amortized cost and fair value. The estimated recoverable value is the present value of cash flows expected to be collected, as determined by management. The difference between fair value and amortized cost that is not associated with credit-related factors is recognized in the Condensed Consolidated Statements of Comprehensive Income (Loss). Accrued interest is excluded from the measurement of the allowance for credit losses. When determining if a credit loss has been incurred, we may consider the historical performance of the security, available market information and security specific considerations such as the priority payment of the security. In addition, inputs used in our analysis include, but are not limited to, credit ratings and downgrades, delinquency rates, missed scheduled interest or principal payments, purchase yields, underlying asset performance, collateral types, modeled default rates, modeled severity rates, call/prepayment rates, expected cash flows, industry concentrations, and potential or filed bankruptcies or restructurings. We evaluate for credit losses each quarter. If we determine that all or a portion of a fixed maturity is uncollectible, the uncollectible amortized cost is written off with a corresponding reduction to the allowance for credit losses. If we collect cash flows that were previously written off, the recovery is recognized in realized investment gains. We also consider whether we intend to sell an available-for-sale security or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in Net realized investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss) based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security.
Disclosures about Fair Value of Financial Instruments	Disclosures About Fair Value of Financial Instruments Cash. The carrying amount approximates fair value. Investment securities and short-term investments. See Note 3, “Investments,” for additional information. Premiums receivable and reinsurance recoverables on paid losses. The carrying value of current receivables and reinsurance recoverables on paid losses approximates fair value. Debt. At March 31, 2022 and December 31, 2021, the fair value of our debt instruments is determined using both Level 1 and Level 2 inputs, as previously defined in Note 3, “Investments.” We receive fair value prices from third-party pricing services for our financial instruments as well as for similar financial instruments. These prices are determined using observable market information such as publicly traded quoted prices, and trading prices for similar financial instruments actively being traded in the current market. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of March 31, 2022 and December 31, 2021. A description of the valuation techniques we use to measure these liabilities at fair value is as follows: Senior Unsecured Fixed Rate Notes Level 1: • Our senior unsecured fixed rate notes are valued using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Junior Subordinated Debentures and Floating Rate Loan Stock Level 2: • Our trust preferred debentures, subordinated debentures and floating rate loan stock are typically valued using Level 2 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices for similar securities being traded in active markets at the reporting date, as our specific debt instruments are more infrequently traded.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments	The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: March 31, 2022 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 496.0 $ 0.4 $ 17.0 $ — $ 479.4 Foreign Governments 211.7 3.7 7.6 0.3 207.5 Obligations of states and political subdivisions 169.6 2.3 4.9 0.4 166.6 Corporate bonds 2,009.0 9.7 86.2 2.1 1,930.4 Commercial mortgage-backed securities 422.7 0.6 23.1 — 400.2 Residential mortgage-backed securities 455.4 1.9 26.5 — 430.8 Asset-backed securities 205.6 0.3 5.3 0.1 200.5 Collateralized loan obligations 332.7 0.6 4.8 — 328.5 Total fixed maturities $ 4,302.7 $ 19.5 $ 175.4 $ 2.9 $ 4,143.9 December 31, 2021 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 422.7 $ 5.5 $ 3.2 $ — $ 425.0 Foreign Governments 234.7 2.2 3.9 0.2 232.8 Obligations of states and political subdivisions 166.7 5.8 1.2 — 171.3 Corporate bonds 1,972.3 33.5 20.3 2.2 1,983.3 Commercial mortgage-backed securities 416.7 6.3 4.3 — 418.7 Residential mortgage-backed securities 480.7 7.5 5.7 — 482.5 Asset-backed securities 173.0 1.3 0.6 0.1 173.6 Collateralized loan obligations 336.4 1.3 1.6 — 336.1 Total fixed maturities $ 4,203.2 $ 63.4 $ 40.8 $ 2.5 $ 4,223.3
Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity	The amortized cost and fair values of fixed maturity investments as of March 31, 2022, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 229.3 $ 232.1 Due after one year through five years 1,849.4 1,795.6 Due after five years through ten years 719.4 673.7 Due after ten years 88.2 82.5 Structured securities 1,416.4 1,360.0 Total $ 4,302.7 $ 4,143.9
Schedule of Carrying Value and Unfunded Investment Commitments of Other Invested Assets Portfolio	Details regarding the carrying value and unfunded investment commitments of other investments as of March 31, 2022 and December 31, 2021 were as follows: March 31, 2022 (in millions) Carrying Unfunded Investment Type Hedge funds $ 58.1 $ — Private equity 259.6 68.8 Overseas deposits 83.6 — Commercial Mortgage Loans 46.5 — Other 4.7 — Total other investments $ 452.5 $ 68.8 December 31, 2021 (in millions) Carrying Unfunded Investment Type Hedge funds $ 58.6 $ — Private equity 248.9 64.2 Overseas deposits 74.9 — Other 4.8 — Total other investments $ 387.2 $ 64.2
Schedule of Aging of Unrealized Losses on Company's Investments in Fixed Maturities, Equity Securities and Other Investments	An aging of unrealized losses on our investments in fixed maturities is presented below: March 31, 2022 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 416.1 $ 12.8 $ 49.6 $ 4.2 $ 465.7 $ 17.0 Foreign Governments 150.2 6.7 25.4 0.9 175.6 7.6 Obligations of states and political subdivisions 78.7 4.7 3.0 0.2 81.7 4.9 Corporate bonds 1,275.0 62.9 219.6 23.3 1,494.6 86.2 Commercial mortgage-backed securities 296.8 17.8 41.7 5.3 338.5 23.1 Residential mortgage-backed securities 234.6 13.8 120.7 12.7 355.3 26.5 Asset-backed securities 135.9 4.7 7.0 0.6 142.9 5.3 Collateralized loan obligations 274.8 4.8 1.0 — 275.8 4.8 Total fixed maturities $ 2,862.1 $ 128.2 $ 468.0 $ 47.2 $ 3,330.1 $ 175.4 December 31, 2021 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 193.4 $ 2.6 $ 14.6 $ 0.6 $ 208.0 $ 3.2 Foreign Governments 152.4 3.3 2.6 0.6 155.0 3.9 Obligations of states and political subdivisions 46.0 0.8 0.1 0.4 46.1 1.2 Corporate bonds 854.3 18.3 41.7 2.0 896.0 20.3 Commercial mortgage-backed securities 198.8 4.1 6.5 0.2 205.3 4.3 Residential mortgage-backed securities 284.2 5.6 4.0 0.1 288.2 5.7 Asset-backed securities 62.6 0.6 — — 62.6 0.6 Collateralized loan obligations 176.1 1.6 0.5 — 176.6 1.6 Total fixed maturities $ 1,967.8 $ 36.9 $ 70.0 $ 3.9 $ 2,037.8 $ 40.8
Debt Securities, Available-for-sale, Allowance for Credit Loss	The following table presents a roll-forward of the changes in allowance for credit losses on available-for-sale fixed maturities by industry category for the three months ending March 31, 2022 and 2021, respectively: (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2022 $ 0.2 $ — $ 2.2 $ 0.1 $ 2.5 Securities for which allowance was not previously recorded 0.1 — 0.4 — 0.5 Securities sold during the period — — (0.6) — (0.6) Additional net increases (decreases) in existing allowance — 0.4 0.1 — 0.5 Ending balance, March 31, 2022 $ 0.3 $ 0.4 $ 2.1 $ 0.1 $ 2.9 (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2021 $ 0.2 $ 0.1 $ 6.1 $ 0.2 $ 6.6 Securities for which allowance was not previously recorded — — 2.1 — 2.1 Securities sold during the period — — (0.4) — (0.4) Additional net increases (decreases) in existing allowance (0.1) (0.1) (0.7) (0.2) (1.1) Ending balance, March 31, 2021 $ 0.1 $ — $ 7.1 $ — $ 7.2
Schedule of Company's Gross Realized Investment Gains (Losses)	The following table presents our gross realized investment gains and losses: For the Three Months Ended (in millions) 2022 2021 Realized gains on fixed maturities and other Fixed maturities $ 11.2 $ 5.5 Other investments, including short-terms 1.5 6.0 12.7 11.5 Realized losses on fixed maturities and other Fixed maturities (16.6) (1.5) Other investments, including short-terms (6.8) (9.5) (23.4) (11.0) Net (losses) recognized on fixed maturities and other Credit losses on fixed maturities (1.0) (1.1) Other (1) (28.5) — (29.5) (1.1) Equity securities Net realized gains (losses) on equity securities (1.0) (1.8) Change in unrealized gains (losses) on equity securities held at the end of the period 6.7 15.5 Net realized gains (losses) on equity securities 5.7 13.7 Net realized investment and other gains (losses) before income taxes (34.5) 13.1 Income tax (benefit) provision (0.7) 2.6 Net realized investment and other gains (losses), net of income taxes $ (33.8) $ 10.5 (1) Refer to the sale of Argo Seguros in Note 1, “Basis of Presentation” for additional information.
Schedule of Changes in Unrealized Appreciation (Depreciation)	Changes in unrealized gains (losses) related to investments are summarized as follows: For the Three Months Ended (in millions) 2022 2021 Change in unrealized gains (losses) Fixed maturities $ (177.9) $ (65.7) Other and short-term investments 0.1 (0.4) Net unrealized investment gains (losses) before income taxes (177.8) (66.1) Income tax provision (benefit) (33.9) (12.6) Net unrealized investment gains (losses), net of income taxes $ (143.9) $ (53.5)
Schedule of Fair Value of Foreign Currency Exchange Forward Contracts	The fair value of our foreign currency exchange forward contracts as of March 31, 2022 and December 31, 2021 was as follows: (in millions) March 31, 2022 December 31, 2021 Operational currency exposure $ (8.5) $ (0.3) Asset manager investment exposure 0.8 (0.3) Total $ (7.7) $ (0.6)
Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts	The following table represents our gross realized investment gains and losses on our foreign currency exchange forward contracts: For the Three Months Ended (in millions) 2022 2021 Realized gains Operational currency exposure $ 2.5 $ 3.9 Asset manager investment exposure 1.1 1.0 Total return strategy — 8.5 Gross realized investment gains 3.6 13.4 Realized losses Operational currency exposure (8.8) (9.2) Total return strategy — (7.5) Gross realized investment losses (8.8) (16.7) Net realized investment (losses) gains on foreign currency exchange forward contracts $ (5.2) $ (3.3)
Schedule of Restricted Assets	The following table presents our components of restricted assets: (in millions) March 31, 2022 December 31, 2021 Securities on deposit for regulatory and other purposes $ 177.0 $ 195.6 Securities pledged as collateral for letters of credit and other 185.4 193.9 Securities and cash on deposit supporting Lloyd’s business (1) 290.9 296.8 Total restricted investments $ 653.3 $ 686.3 (1) Argo Group is required to maintain Funds at Lloyd’s (“FAL”) to support it business for Syndicate 1200 and Syndicate 1910. At March 31, 2022 the amount pledged for FAL was $290.9 million, of which $137.6 million was provided by Argo Re Ltd.
Financial Assets Measured at Fair Value on Recurring Basis	Based on an analysis of the inputs, our financial assets measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 479.5 $ 472.2 $ 7.3 $ — Foreign Governments 207.5 — 207.5 — Obligations of states and political subdivisions 166.6 — 166.6 — Corporate bonds 1,930.3 — 1,915.3 15.0 Commercial mortgage-backed securities 400.2 — 400.2 — Residential mortgage-backed securities 430.8 — 430.8 — Asset-backed securities 200.5 — 179.3 21.2 Collateralized loan obligations 328.5 — 328.5 — Total fixed maturities 4,143.9 472.2 3,635.5 36.2 Equity securities 54.0 36.4 — 17.6 Other investments 84.0 — 84.0 — Short-term investments 421.1 419.9 1.2 — $ 4,703.0 $ 928.5 $ 3,720.7 $ 53.8 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (a) Level 2 (b) Level 3 (c) Fixed maturities U.S. Governments $ 425.0 $ 417.4 $ 7.6 $ — Foreign Governments 232.8 — 232.8 — Obligations of states and political subdivisions 171.3 — 171.3 — Corporate bonds 1,983.3 — 1,980.5 2.8 Commercial mortgage-backed securities 418.7 — 418.7 — Residential mortgage-backed securities 482.5 — 482.5 — Asset-backed securities 173.6 — 173.6 — Collateralized loan obligations 336.1 — 336.1 — Total fixed maturities 4,223.3 417.4 3,803.1 2.8 Equity securities 56.3 41.6 — 14.7 Other investments 75.4 — 75.4 — Short-term investments 655.8 653.9 1.9 — $ 5,010.8 $ 1,112.9 $ 3,880.4 $ 17.5 (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs
Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3	A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Unobservable Inputs (Level 3) (in millions) Credit Financial Equity Total Beginning balance, January 1, 2022 $ 2.8 $ 14.7 $ 17.5 Transfers into Level 3 34.7 0.1 34.8 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income (0.4) 1.8 1.4 Included in other comprehensive income 0.8 — 0.8 Purchases, issuances, sales, and settlements: Purchases — 1.0 1.0 Issuances — — — Sales (1.7) — (1.7) Settlements — — — Ending balance, March 31, 2022 $ 36.2 $ 17.6 $ 53.8 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2021 $ — $ — $ — (in millions) Credit Financial Equity Total Beginning balance, January 1, 2021 $ 7.0 $ 17.5 $ 24.5 Transfers into Level 3 — 1.0 1.0 Transfers out of Level 3 — — — Total gains or losses (realized/unrealized): Included in net income — 4.2 4.2 Included in other comprehensive loss (0.8) — (0.8) Purchases, issuances, sales, and settlements: Purchases 0.1 1.2 1.3 Issuances — — — Sales (3.5) (10.6) (14.1) Settlements — — — Ending balance, December 31, 2021 $ 2.8 $ 13.3 $ 16.1 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2020 $ — $ — $ —

Allowance for Credit Losses (Ta

Allowance for Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2022
Credit Loss [Abstract]
Premium Receivable, Allowance for Credit Loss	The following table represents the balances of premiums receivable, net of allowance for expected credit losses, at March 31, 2022 and January 1, 2022, and the changes in the allowance for expected credit losses for the three months ended March 31, 2022. (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Balance, January 1, 2022 $ 648.6 $ 5.7 Current period change for estimated uncollectible premiums (0.4) Write-offs of uncollectible premiums receivable — Balance, March 31, 2022 $ 649.3 $ 5.3
Reinsurance Recoverable, Allowance for Credit Loss	Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, at March 31, 2022 and January 1, 2022, and changes in the allowance for estimated uncollectible reinsurance for the three months ended March 31, 2022. (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Balance, January 1, 2022 $ 2,966.4 $ 3.8 Current period change for estimated uncollectible reinsurance — Write-offs of uncollectible reinsurance recoverables — Balance, March 31, 2022 $ 2,857.9 $ 3.8

Reserves for Losses and Loss _2

Reserves for Losses and Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 2022
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): For the Three Months Ended (in millions) 2022 2021 Net reserves beginning of the year $ 3,123.2 $ 2,906.1 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 280.2 306.6 Prior accident years 3.4 1.0 Losses and LAE incurred during calendar year, net of reinsurance 283.6 307.6 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 19.0 33.0 Prior accident years 266.1 230.3 Losses and LAE payments made during current calendar year, net of reinsurance: 285.1 263.3 Divestitures (1) (31.0) — Net reserve ceded - reinsurance to close transaction for years of account 2017 and prior (2) — 207.8 Change in participation interest (3) 48.0 19.8 Foreign exchange adjustments (0.4) (0.8) Net reserves - end of period 3,138.3 2,761.6 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,509.8 2,373.7 Gross reserves - end of period $ 5,648.1 $ 5,135.3 (1) Refer to the sale of Argo Seguros in Note 1, “Basis of Presentation” for additional information. (2) Amount represents reserves ceded under the reinsurance to close transaction with RiverStone for Lloyd’s years of account 2017 and prior, effective January 1, 2021. (3) Amount represents the change in reserves due to changing our participation in Syndicates 1200 and 1910.
Impact from (Favorable) Unfavorable Development of Prior Accident Years’ Loss and LAE Reserves on Each Reporting Segment	The impact from the (favorable) unfavorable development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: For the Three Months Ended (in millions) 2022 2021 U.S. Operations $ 5.0 $ (0.4) International Operations (3.0) — Run-off Lines 1.4 1.4 Total (favorable) unfavorable prior-year development $ 3.4 $ 1.0

Disclosures about Fair Value _2

Disclosures about Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value	A summary of our financial instruments whose carrying value did not equal fair value is shown below: March 31, 2022 December 31, 2021 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 172.7 $ 173.2 $ 172.7 $ 172.9 Subordinated debentures 85.6 92.1 85.5 91.9 Total junior subordinated debentures 258.3 265.3 258.2 264.8 Senior unsecured fixed rate notes 140.4 144.1 140.3 148.4 Floating rate loan stock 57.3 57.4 57.0 57.1 $ 456.0 $ 466.8 $ 455.5 $ 470.3
Fair Value, Assets Measured on Recurring and Nonrecurring Basis	Based on an analysis of the inputs, our financial instruments measured at fair value for disclosure purposes have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) March 31, 2022 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 173.2 $ — $ 173.2 $ — Subordinated debentures 92.1 — 92.1 — Total junior subordinated debentures 265.3 — 265.3 — Senior unsecured fixed rate notes 144.1 144.1 — — Floating rate loan stock 57.4 — 57.4 — $ 466.8 $ 144.1 $ 322.7 $ — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2021 Level 1 (a) Level 2 (b) Level 3 (c) Junior subordinated debentures: Trust preferred debentures $ 172.9 $ — $ 172.9 $ — Subordinated debentures 91.9 — 91.9 — Total junior subordinated debentures 264.8 — 264.8 — Senior unsecured fixed rate notes 148.4 148.4 — — Floating rate loan stock 57.1 — 57.1 — $ 470.3 $ 148.4 $ 321.9 $ — (a) Quoted prices in active markets for identical assets (b) Significant other observable inputs (c) Significant unobservable inputs

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Changes in Accumulated Other Comprehensive (Loss) Income	A summary of changes in accumulated other comprehensive (loss) income, net of taxes (where applicable) by component for the three months ended March 31, 2022 and 2021 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2022 $ (35.3) $ 19.7 $ (7.1) $ (22.7) Other comprehensive income (loss) before reclassifications 4.1 (139.2) — (135.1) Amounts reclassified from accumulated other comprehensive loss 27.3 (4.4) — 22.9 Net current-period other comprehensive income (loss) 31.4 (143.6) — (112.2) Balance, March 31, 2022 $ (3.9) $ (123.9) $ (7.1) $ (134.9) (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2021 $ (37.9) $ 105.1 $ (8.6) $ 58.6 Other comprehensive loss before reclassifications (0.9) (50.3) — (51.2) Amounts reclassified from accumulated other comprehensive loss — (3.2) — (3.2) Net current-period other comprehensive loss (0.9) (53.5) — (54.4) Balance, March 31, 2021 $ (38.8) $ 51.6 $ (8.6) $ 4.2
Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income	The amounts reclassified from accumulated other comprehensive income (loss) shown in the above table have been included in the following captions in our Condensed Consolidated Statements of Income (Loss): For the Three Months Ended (in millions) 2022 2021 Unrealized gains and losses on securities: Net realized investment gains $ (5.4) $ (4.0) Provision for income taxes 1.0 0.8 Foreign currency translation adjustments: Net realized investment and other gains (losses) 27.3 — Total, net of taxes $ 22.9 $ (3.2)

Net Income (Loss) Per Common _2

Net Income (Loss) Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share on Basic and Diluted Basis	The following table presents the calculation of net income (loss) per common share on a basic and diluted basis: For the Three Months Ended (in millions, except number of shares and per share amounts) 2022 2021 Net income (loss) $ (1.0) $ 29.8 Less: Preferred share dividends 2.6 2.6 Net income (loss) attributable to common shareholders (3.6) 27.2 Weighted average common shares outstanding - basic 34,891,935 34,712,650 Effect of dilutive securities: Equity compensation awards — 225,363 Weighted average common shares outstanding - diluted 34,891,935 34,938,013 Net income (loss) per common share: Basic $ (0.11) $ 0.78 Diluted $ (0.11) $ 0.78

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2022
Supplemental Cash Flow Elements [Abstract]
Schedule of Interest Paid and Income Taxes Paid (Recovered)	Interest paid and income taxes paid (recovered) were as follows: For the Three Months Ended (in millions) 2022 2021 Senior unsecured fixed rate notes $ 2.3 $ 2.3 Junior subordinated debentures 2.5 2.5 Other indebtedness 0.8 0.8 Total interest paid $ 5.6 $ 5.6 Income taxes paid $ 0.3 $ 0.9 Income taxes recovered (0.2) (0.1) Income taxes paid, net $ 0.1 $ 0.8

Share-based Compensation (Table

Share-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Summary of Restricted Share Activity	A summary of non-vested restricted share activity as of March 31, 2022 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2022 278,430 $ 49.57 Granted 240,677 41.00 Reclassed from performance shares 14,373 32.61 Vested and issued (83,101) 46.32 Expired or forfeited (13,379) 48.72 Outstanding at March 31, 2022 437,000 $ 44.58
Schedule of Performance Shares	A summary of non-vested performance share activity as of March 31, 2022 and changes during the three months then ended is as follows: Shares Weighted-Average Outstanding at January 1, 2022 200,564 $ 47.52 Granted 125,074 41.00 Reclassed to restricted shares (14,373) 32.61 Vested and issued (1,831) 68.27 Expired or forfeited (17,398) 59.03 Outstanding at March 31, 2022 292,036 $ 44.64

Underwriting, Acquisition and_2

Underwriting, Acquisition and Insurance Expenses (Tables)	3 Months Ended
	Mar. 31, 2022
Underwriting, Acquisition and Insurance Expenses [Abstract]
Underwriting, Acquisition and Insurance Expenses	Underwriting, acquisition and insurance expenses were as follows: For the Three Months Ended (in millions) 2022 2021 Commissions $ 77.9 $ 76.5 Other underwriting and insurance expenses 103.2 106.6 Total underwriting, acquisition and insurance expenses before deferral 181.1 183.1 Net deferral of policy acquisition costs (8.2) (6.7) Total underwriting, acquisition and insurance expenses $ 172.9 $ 176.4

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates	For the three months ended March 31, 2022 and 2021, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: For the Three Months Ended March 31, 2022 2021 (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ (0.2) — % $ 5.0 — % United States 38.8 21.9 % 41.3 15.7 % United Kingdom 5.0 80.8 % (18.3) 28.1 % Brazil (0.1) (422.4) % 1.6 — % United Arab Emirates 0.6 — % 0.3 — % Ireland (33.3) — % (0.1) — % Italy 0.1 138.1 % 0.9 — % Malta 1.1 — % 0.5 — % Pre-tax income $ 12.0 109.7 % $ 31.2 4.3 %
Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate	A reconciliation of the difference between the provision for income taxes and the expected tax provision at the weighted average tax rate is as follows: For the Three Months Ended (in millions) 2022 2021 Income tax provision at expected rate $ 9.4 $ 6.3 Tax effect of: Nontaxable investment income (0.1) (0.2) Foreign exchange adjustments 0.1 (0.2) Sale of Brazil Operations 1.6 — Change in uncertain tax position liability 0.1 (2.4) Change in valuation allowance (1.8) (0.8) Impact of change in tax rate related to Finance Act 2021 0.5 — Lease termination 2.0 — Other 1.2 (1.3) Income tax provision $ 13.0 $ 1.4

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2022
Segment Reporting [Abstract]
Revenue and Income (Loss) Before Income Taxes for Each Segment	Revenue and income (loss) before income taxes for each segment were as follows: For the Three Months Ended (in millions) 2022 2021 Revenue: Earned premiums U.S. Operations $ 336.4 $ 314.4 International Operations 144.2 151.5 Run-off Lines — 0.2 Total earned premiums 480.6 466.1 Net investment income U.S. Operations 25.6 28.8 International Operations 11.4 12.0 Run-off Lines 0.7 0.8 Corporate and Other — 2.8 Total net investment income 37.7 44.4 Net realized investment and other gains (losses) (34.5) 13.1 Total revenue $ 483.8 $ 523.6 For the Three Months Ended (in millions) 2022 2021 Income (loss) before income taxes U.S. Operations $ 43.9 $ 36.6 International Operations 22.7 (11.8) Run-off Lines (1.0) 0.6 Total segment income (loss) before income taxes 65.6 25.4 Corporate and Other (16.2) (6.0) Net realized investment and other gains (losses) (34.5) 13.1 Foreign currency exchange losses (2.9) (1.3) Total income (loss) before income taxes $ 12.0 $ 31.2
Schedule of Earned Premiums by Geographic Location	The table below presents earned premiums by geographic location for the three months ended March 31, 2022 and 2021. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. For the Three Months Ended (in millions) 2022 2021 United States $ 336.4 $ 312.8 United Kingdom 127.1 99.0 Bermuda 6.4 25.1 Malta 2.3 14.0 All other jurisdictions 8.4 15.2 Total earned premiums $ 480.6 $ 466.1
Identifiable Assets	The following table represents identifiable assets: (in millions) March 31, 2022 December 31, 2021 U.S. Operations $ 5,716.2 $ 5,800.1 International Operations 3,780.9 3,932.3 Run-off Lines 305.3 314.7 Corporate and Other 178.6 270.7 Total $ 9,981.0 $ 10,317.8

Basis of Presentation - Sale of

Basis of Presentation - Sale of Business Unit (Details) - Disposal Group, Disposed of by Sale, Not Discontinued Operations - Argo Seguros Brasil S.A. R$ in Millions, $ in Millions	Feb. 15, 2022USD ($)	Dec. 31, 2021USD ($)	Feb. 15, 2022BRL (R$)	Feb. 15, 2022USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration received from sale			R$ 160	$ 30.5
Gain on disposal	$ (28.5)	$ (6.3)

Investments - Additional Inform

Investments - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)security	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Fair value of investments, assets managed on behalf of the trade capital providers | $	$ 71.2		$ 89.6
Number of securities in an unrealized loss position, total | security	5,203
Number of securities in an unrealized loss position for less than one year | security	1,080
Number of securities in an unrealized loss position for a period of one year or greater | security	208
Credit losses on fixed maturities | $	$ 1	$ 1.1
Gain (Loss) on Investments
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Credit losses on fixed maturities | $	$ 1	$ 1.1

Investments - Schedule of Amort

Investments - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Fixed maturities
Amortized Cost	$ 4,302.7	$ 4,203.2
Allowance for Credit Losses	2.9	2.5	$ 7.2	$ 6.6
Fair Value	4,143.9	4,223.3
Fixed maturities
Fixed maturities
Amortized Cost	4,302.7	4,203.2
Gross Unrealized Gains	19.5	63.4
Gross Unrealized Losses	175.4	40.8
Allowance for Credit Losses	2.9	2.5
Fair Value	4,143.9	4,223.3
Fixed maturities | U.S. Governments
Fixed maturities
Amortized Cost	496	422.7
Gross Unrealized Gains	0.4	5.5
Gross Unrealized Losses	17	3.2
Allowance for Credit Losses	0	0
Fair Value	479.4	425
Fixed maturities | Foreign Governments
Fixed maturities
Amortized Cost	211.7	234.7
Gross Unrealized Gains	3.7	2.2
Gross Unrealized Losses	7.6	3.9
Allowance for Credit Losses	0.3	0.2
Fair Value	207.5	232.8
Fixed maturities | Obligations of states and political subdivisions
Fixed maturities
Amortized Cost	169.6	166.7
Gross Unrealized Gains	2.3	5.8
Gross Unrealized Losses	4.9	1.2
Allowance for Credit Losses	0.4	0
Fair Value	166.6	171.3
Fixed maturities | Corporate bonds
Fixed maturities
Amortized Cost	2,009	1,972.3
Gross Unrealized Gains	9.7	33.5
Gross Unrealized Losses	86.2	20.3
Allowance for Credit Losses	2.1	2.2
Fair Value	1,930.4	1,983.3
Fixed maturities | Commercial mortgage-backed securities
Fixed maturities
Amortized Cost	422.7	416.7
Gross Unrealized Gains	0.6	6.3
Gross Unrealized Losses	23.1	4.3
Allowance for Credit Losses	0	0
Fair Value	400.2	418.7
Fixed maturities | Residential mortgage-backed securities
Fixed maturities
Amortized Cost	455.4	480.7
Gross Unrealized Gains	1.9	7.5
Gross Unrealized Losses	26.5	5.7
Allowance for Credit Losses	0	0
Fair Value	430.8	482.5
Fixed maturities | Asset-backed securities
Fixed maturities
Amortized Cost	205.6	173
Gross Unrealized Gains	0.3	1.3
Gross Unrealized Losses	5.3	0.6
Allowance for Credit Losses	0.1	0.1
Fair Value	200.5	173.6
Fixed maturities | Collateralized loan obligations
Fixed maturities
Amortized Cost	332.7	336.4
Gross Unrealized Gains	0.6	1.3
Gross Unrealized Losses	4.8	1.6
Allowance for Credit Losses	0	0
Fair Value	$ 328.5	$ 336.1

Investments - Schedule of Amo_2

Investments - Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity (Detail) $ in Millions	Mar. 31, 2022USD ($)
Amortized Cost
Due in one year or less	$ 229.3
Due after one year through five years	1,849.4
Due after five years through ten years	719.4
Due after ten years	88.2
Structured securities	1,416.4
Total	4,302.7
Fair Value
Due in one year or less	232.1
Due after one year through five years	1,795.6
Due after five years through ten years	673.7
Due after ten years	82.5
Structured securities	1,360
Total	$ 4,143.9

Investments - Schedule of Carry

Investments - Schedule of Carrying Value and Unfunded Investment Commitments of Other Invested Assets Portfolio (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Carrying Value	$ 5,071.5	$ 5,322.6
Hedge funds
Schedule of Investments [Line Items]
Carrying Value	58.1	58.6
Unfunded Commitments	0	0
Private equity
Schedule of Investments [Line Items]
Carrying Value	259.6	248.9
Unfunded Commitments	68.8	64.2
Overseas deposits
Schedule of Investments [Line Items]
Carrying Value	83.6	74.9
Unfunded Commitments	0	0
Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Carrying Value	46.5
Unfunded Commitments	0
Other
Schedule of Investments [Line Items]
Carrying Value	4.7	4.8
Unfunded Commitments	0	0
Other Investments
Schedule of Investments [Line Items]
Carrying Value	452.5	387.2
Unfunded Commitments	$ 68.8	$ 64.2

Investments - Schedule of Aging

Investments - Schedule of Aging of Unrealized Losses on Company's Investments in Fixed Maturities, Equity Securities and Other Investments (Detail) - Fixed maturities - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	$ 2,862.1	$ 1,967.8
Unrealized Losses, Less Than One Year	128.2	36.9
Fair Value, One Year or Greater	468	70
Unrealized Losses, One Year or Greater	47.2	3.9
Fair Value, Total	3,330.1	2,037.8
Unrealized Losses, Total	175.4	40.8
U.S. Governments
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	416.1	193.4
Unrealized Losses, Less Than One Year	12.8	2.6
Fair Value, One Year or Greater	49.6	14.6
Unrealized Losses, One Year or Greater	4.2	0.6
Fair Value, Total	465.7	208
Unrealized Losses, Total	17	3.2
Foreign Governments
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	150.2	152.4
Unrealized Losses, Less Than One Year	6.7	3.3
Fair Value, One Year or Greater	25.4	2.6
Unrealized Losses, One Year or Greater	0.9	0.6
Fair Value, Total	175.6	155
Unrealized Losses, Total	7.6	3.9
Obligations of states and political subdivisions
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	78.7	46
Unrealized Losses, Less Than One Year	4.7	0.8
Fair Value, One Year or Greater	3	0.1
Unrealized Losses, One Year or Greater	0.2	0.4
Fair Value, Total	81.7	46.1
Unrealized Losses, Total	4.9	1.2
Corporate bonds
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	1,275	854.3
Unrealized Losses, Less Than One Year	62.9	18.3
Fair Value, One Year or Greater	219.6	41.7
Unrealized Losses, One Year or Greater	23.3	2
Fair Value, Total	1,494.6	896
Unrealized Losses, Total	86.2	20.3
Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	296.8	198.8
Unrealized Losses, Less Than One Year	17.8	4.1
Fair Value, One Year or Greater	41.7	6.5
Unrealized Losses, One Year or Greater	5.3	0.2
Fair Value, Total	338.5	205.3
Unrealized Losses, Total	23.1	4.3
Residential mortgage-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	234.6	284.2
Unrealized Losses, Less Than One Year	13.8	5.6
Fair Value, One Year or Greater	120.7	4
Unrealized Losses, One Year or Greater	12.7	0.1
Fair Value, Total	355.3	288.2
Unrealized Losses, Total	26.5	5.7
Asset-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	135.9	62.6
Unrealized Losses, Less Than One Year	4.7	0.6
Fair Value, One Year or Greater	7	0
Unrealized Losses, One Year or Greater	0.6	0
Fair Value, Total	142.9	62.6
Unrealized Losses, Total	5.3	0.6
Collateralized loan obligations
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	274.8	176.1
Unrealized Losses, Less Than One Year	4.8	1.6
Fair Value, One Year or Greater	1	0.5
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	275.8	176.6
Unrealized Losses, Total	$ 4.8	$ 1.6

Investments - Allowance for Cre

Investments - Allowance for Credit Losses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, December 31, 2021	$ 2.5	$ 6.6
Securities for which allowance was not previously recorded	0.5	2.1
Securities sold during the period	(0.6)	(0.4)
Additional net increases (decreases) in existing allowance	0.5	(1.1)
Ending balance, March 31, 2022	2.9	7.2
Foreign Governments
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, December 31, 2021	0.2	0.2
Securities for which allowance was not previously recorded	0.1	0
Securities sold during the period	0	0
Additional net increases (decreases) in existing allowance	0	(0.1)
Ending balance, March 31, 2022	0.3	0.1
Obligations of states and political subdivisions
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, December 31, 2021	0	0.1
Securities for which allowance was not previously recorded	0	0
Securities sold during the period	0	0
Additional net increases (decreases) in existing allowance	0.4	(0.1)
Ending balance, March 31, 2022	0.4	0
Corporate bonds
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, December 31, 2021	2.2	6.1
Securities for which allowance was not previously recorded	0.4	2.1
Securities sold during the period	(0.6)	(0.4)
Additional net increases (decreases) in existing allowance	0.1	(0.7)
Ending balance, March 31, 2022	2.1	7.1
Asset-backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance, December 31, 2021	0.1	0.2
Securities for which allowance was not previously recorded	0	0
Securities sold during the period	0	0
Additional net increases (decreases) in existing allowance	0	(0.2)
Ending balance, March 31, 2022	$ 0.1	$ 0

Investments - Schedule of Compa

Investments - Schedule of Company's Gross Realized Investment Gains (Losses) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	$ 12.7	$ 11.5
Realized losses on fixed maturities and other	(23.4)	(11)
Credit losses on fixed maturities	1	1.1
Other(1)	(28.5)	0
Net (losses) recognized on fixed maturities and other	(29.5)	(1.1)
Net realized gains (losses) on equity securities	(1)	(1.8)
Change in unrealized gains (losses) on equity securities held at the end of the period	6.7	15.5
Net realized gains (losses) on equity securities	5.7	13.7
Net realized investment and other gains (losses) before income taxes	(34.5)	13.1
Income tax (benefit) provision	(0.7)	2.6
Net realized investment and other gains (losses), net of income taxes	(33.8)	10.5
Fixed maturities
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	11.2	5.5
Realized losses on fixed maturities and other	(16.6)	(1.5)
Other investments
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other	1.5	6
Realized losses on fixed maturities and other	(6.8)	(9.5)
Other than temporary impairment losses
Schedule of Investments [Line Items]
Credit losses on fixed maturities	$ (1)	$ (1.1)

Investments - Schedule of Chang

Investments - Schedule of Changes in Unrealized Appreciation (Depreciation) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	$ (177.8)	$ (66.1)
Income tax provision (benefit)	(33.9)	(12.6)
Net unrealized investment gains (losses), net of income taxes	(143.9)	(53.5)
Fixed maturities
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	(177.9)	(65.7)
Other and short-term investments
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	$ 0.1	$ (0.4)

Investments - Schedule of Fair

Investments - Schedule of Fair Value of Foreign Currency Exchange Forward Contracts (Detail) - Foreign Currency Exchange Forward Contracts - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ (7.7)	$ (0.6)
Operational currency exposure
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	(8.5)	(0.3)
Asset manager investment exposure
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ 0.8	$ (0.3)

Investments - Schedule of Reali

Investments - Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts (Detail) - Foreign Currency Exchange Forward Contracts - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule of Investments [Line Items]
Gross realized investment gains	$ 3.6	$ 13.4
Gross realized investment losses	(8.8)	(16.7)
Net realized investment (losses) gains on foreign currency exchange forward contracts	(5.2)	(3.3)
Operational currency exposure
Schedule of Investments [Line Items]
Gross realized investment gains	2.5	3.9
Gross realized investment losses	(8.8)	(9.2)
Asset manager investment exposure
Schedule of Investments [Line Items]
Gross realized investment gains	1.1	1
Total return strategy
Schedule of Investments [Line Items]
Gross realized investment gains	0	8.5
Gross realized investment losses	$ 0	$ (7.5)

Investments - Components of Res

Investments - Components of Restricted Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities pledged as collateral for letters of credit and other	$ 185.4	$ 193.9
Securities and cash on deposit supporting Lloyd's business	290.9	296.8
Total restricted investments	653.3	686.3
Securities required to be maintained at Lloyd's	290.9
Argo Re
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities and cash on deposit supporting Lloyd's business	137.6
Securities Deposits for Regulatory and Other Purposes
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities on deposit for regulatory and other purposes	$ 177	$ 195.6

Investments - Financial Assets

Investments - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	$ 5,071.5	$ 5,322.6
Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	4,703	5,010.8
Fair Value, Recurring | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	4,143.9	4,223.3
Fair Value, Recurring | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	328.5	336.1
Fair Value, Recurring | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	479.5	425
Fair Value, Recurring | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	207.5	232.8
Fair Value, Recurring | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	166.6	171.3
Fair Value, Recurring | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	1,930.3	1,983.3
Fair Value, Recurring | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	400.2	418.7
Fair Value, Recurring | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	430.8	482.5
Fair Value, Recurring | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	200.5	173.6
Fair Value, Recurring | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	54	56.3
Fair Value, Recurring | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	84	75.4
Fair Value, Recurring | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	421.1	655.8
Fair Value, Recurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	928.5	1,112.9
Fair Value, Recurring | Level 1 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	472.2	417.4
Fair Value, Recurring | Level 1 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	472.2	417.4
Fair Value, Recurring | Level 1 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	36.4	41.6
Fair Value, Recurring | Level 1 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 1 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	419.9	653.9
Fair Value, Recurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	3,720.7	3,880.4
Fair Value, Recurring | Level 2 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	3,635.5	3,803.1
Fair Value, Recurring | Level 2 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	328.5	336.1
Fair Value, Recurring | Level 2 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	7.3	7.6
Fair Value, Recurring | Level 2 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	207.5	232.8
Fair Value, Recurring | Level 2 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	166.6	171.3
Fair Value, Recurring | Level 2 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	1,915.3	1,980.5
Fair Value, Recurring | Level 2 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	400.2	418.7
Fair Value, Recurring | Level 2 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	430.8	482.5
Fair Value, Recurring | Level 2 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	179.3	173.6
Fair Value, Recurring | Level 2 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 2 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	84	75.4
Fair Value, Recurring | Level 2 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	1.2	1.9
Fair Value, Recurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	53.8	17.5
Fair Value, Recurring | Level 3 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	36.2	2.8
Fair Value, Recurring | Level 3 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	15	2.8
Fair Value, Recurring | Level 3 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	21.2	0
Fair Value, Recurring | Level 3 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	17.6	14.7
Fair Value, Recurring | Level 3 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	0	0
Fair Value, Recurring | Level 3 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	$ 0	$ 0

Investments - Schedule of Recon

Investments - Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3 (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 17.5	$ 24.5
Transfers into Level 3	34.8	1
Transfers out of Level 3	0	0
Included in net income	1.4	4.2
Included in other comprehensive income	0.8	(0.8)
Purchases	1	1.3
Issuances	0	0
Sales	(1.7)	(14.1)
Settlements	0	0
Ending balance		16.1
Ending balance	53.8	17.5
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	0	0
Credit Financial
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2.8	7
Transfers into Level 3	34.7	0
Transfers out of Level 3	0	0
Included in net income	(0.4)	0
Included in other comprehensive income	0.8	(0.8)
Purchases	0	0.1
Issuances	0	0
Sales	(1.7)	(3.5)
Settlements	0	0
Ending balance		2.8
Ending balance	36.2	2.8
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	14.7	17.5
Transfers into Level 3	0.1	1
Transfers out of Level 3	0	0
Included in net income	1.8	4.2
Included in other comprehensive income	0	0
Purchases	1	1.2
Issuances	0	0
Sales	0	(10.6)
Settlements	0	0
Ending balance		13.3
Ending balance	17.6	14.7
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	$ 0	$ 0

Allowance for Credit Losses - P

Allowance for Credit Losses - Premiums Receivable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Credit Loss [Abstract]
Premiums receivable	$ 649.3	$ 648.6
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2022	5.7
Current period change for estimated uncollectible premiums	(0.4)
Write-offs of uncollectible premiums receivable	0
Balance, March 31, 2022	$ 5.3

Allowance for Credit Losses - R

Allowance for Credit Losses - Reinsurance Recoverables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Credit Loss [Abstract]
Reinsurance recoverables, net	$ 2,857.9	$ 2,966.4
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, January 1, 2022	3.8
Current period change for estimated uncollectible reinsurance	0
Write-offs of uncollectible reinsurance recoverables	0
Balance, March 31, 2022	$ 3.8

Reserves for Losses and Loss _3

Reserves for Losses and Loss Adjustment Expenses - Reserves for Losses and Loss Adjustment Expenses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves beginning of the year	$ 3,123.2	$ 2,906.1
Losses and LAE incurred during current calendar year, net of reinsurance:
Current accident year	280.2	306.6
Prior accident years	3.4	1
Losses and LAE incurred during calendar year, net of reinsurance	283.6	307.6
Losses and LAE payments made during current calendar year, net of reinsurance:
Current accident year	19	33
Prior accident years	266.1	230.3
Losses and LAE payments made during current calendar year, net of reinsurance:	285.1	263.3
Divestitures	(31)	0
Net reserve ceded - reinsurance to close transaction for years of account 2017 and prior	0	207.8
Change in participation interest	48	19.8
Foreign exchange adjustments	(0.4)	(0.8)
Net reserves - end of period	3,138.3	2,761.6	$ 3,123.2
Reinsurance recoverables on unpaid losses and LAE, end of period	2,509.8	2,373.7
Gross reserves - end of period	$ 5,648.1	$ 5,135.3	$ 5,595

Reserves for Losses and Loss _4

Reserves for Losses and Loss Adjustment Expenses - Impact from (Favorable) Unfavorable Development of Prior Accident Years' Loss and LAE Reserves on Each Reporting Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total (favorable) unfavorable prior-year development	$ 3.4	$ 1
U.S. Operations
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total (favorable) unfavorable prior-year development	5	(0.4)
International Operations
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total (favorable) unfavorable prior-year development	(3)	0
Run-off Lines
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total (favorable) unfavorable prior-year development	$ 1.4	$ 1.4

Disclosures about Fair Value _3

Disclosures about Fair Value of Financial Instruments - Summary of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 456	$ 455.5
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	466.8	470.3
Junior subordinated debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	258.3	258.2
Junior subordinated debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	265.3	264.8
Junior subordinated debentures | Trust preferred debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	172.7	172.7
Junior subordinated debentures | Trust preferred debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	173.2	172.9
Junior subordinated debentures | Subordinated debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	85.6	85.5
Junior subordinated debentures | Subordinated debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	92.1	91.9
Senior unsecured fixed rate notes | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	140.4	140.3
Senior unsecured fixed rate notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	144.1	148.4
Floating rate loan stock | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	57.3	57
Floating rate loan stock | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 57.4	$ 57.1

Disclosures about Fair Value _4

Disclosures about Fair Value of Financial Instruments - Summary of Fair Values Measured on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	$ 466.8	$ 470.3
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	144.1	148.4
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	322.7	321.9
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	265.3	264.8
Junior subordinated debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	265.3	264.8
Junior subordinated debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Trust preferred debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	173.2	172.9
Junior subordinated debentures | Trust preferred debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Trust preferred debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	173.2	172.9
Junior subordinated debentures | Trust preferred debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Subordinated debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	92.1	91.9
Junior subordinated debentures | Subordinated debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Subordinated debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	92.1	91.9
Junior subordinated debentures | Subordinated debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Senior unsecured fixed rate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	144.1	148.4
Senior unsecured fixed rate notes | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	144.1	148.4
Senior unsecured fixed rate notes | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Senior unsecured fixed rate notes | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Floating rate loan stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	57.4	57.1
Floating rate loan stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Floating rate loan stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	57.4	57.1
Floating rate loan stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	$ 0	$ 0

Shareholders' Equity (Detail)

Shareholders' Equity (Detail) $ / shares in Units, $ in Millions	Mar. 15, 2022USD ($)	Feb. 16, 2022$ / shares	Mar. 15, 2021USD ($)	Mar. 12, 2021USD ($)	Feb. 12, 2021$ / shares	Mar. 31, 2022USD ($)$ / sharesshares	Mar. 31, 2021$ / shares	Dec. 31, 2021$ / shares	May 03, 2016USD ($)
Class of Stock [Line Items]
Cash dividend declared - common shares (in dollars per share)		$ 0.31			$ 0.31	$ 0.31	$ 0.31
Payments of dividends | $	$ 10.8			$ 10.8
Preferred shares par value (in dollars per share)						1		$ 1
Liquidation preference (in dollars per share)						$ 25,000		$ 25,000
Fractional interest per one preference share		0.001			0.001
Depositary shares, dividends per share (in dollars per share)		$ 0.437500			$ 0.43750
Number of shares repurchased (in shares) | shares						0
Series A Preferred Stock
Class of Stock [Line Items]
Payments of dividends | $	$ 2.6		$ 2.6
Preferred stock, dividends declared (in dollars per share)		$ 437.500			$ 437.50
Preferred stock, dividend rate (in percentage)		7.00%			7.00%
Preferred shares par value (in dollars per share)		$ 1			$ 1
Liquidation preference (in dollars per share)		$ 25,000			$ 25,000
2016 Repurchase Authorization
Class of Stock [Line Items]
Total number of shares authorized for purchase | $									$ 150
Remaining number of shares available under repurchase authorization | $						$ 53.3

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,735.2	$ 1,857.8
Other comprehensive income (loss) before reclassifications	(135.1)	(51.2)
Amounts reclassified from accumulated other comprehensive loss	22.9	(3.2)
Net current-period other comprehensive loss	(112.2)	(54.4)
Ending Balance	1,610.8	1,821
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(35.3)	(37.9)
Other comprehensive income (loss) before reclassifications	4.1	(0.9)
Amounts reclassified from accumulated other comprehensive loss	27.3	0
Net current-period other comprehensive loss	31.4	(0.9)
Ending Balance	(3.9)	(38.8)
Unrealized Holding Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	19.7	105.1
Other comprehensive income (loss) before reclassifications	(139.2)	(50.3)
Amounts reclassified from accumulated other comprehensive loss	(4.4)	(3.2)
Net current-period other comprehensive loss	(143.6)	(53.5)
Ending Balance	(123.9)	51.6
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(7.1)	(8.6)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive loss	0	0
Ending Balance	(7.1)	(8.6)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(22.7)	58.6
Ending Balance	$ (134.9)	$ 4.2

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Unrealized gains and losses on securities:
Net realized investment gains	$ (34.5)	$ 13.1
Income tax provision	13	1.4
Net realized investment and other gains (losses)	(40.2)	(1.3)
Net income (loss)	(1)	29.8
Reclassification out of Accumulated Other Comprehensive Income
Unrealized gains and losses on securities:
Net income (loss)	(22.9)	3.2
Unrealized Gains and Losses on Securities | Reclassification out of Accumulated Other Comprehensive Income
Unrealized gains and losses on securities:
Net realized investment gains	5.4	4
Income tax provision	1	0.8
Foreign Currency Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income
Unrealized gains and losses on securities:
Net realized investment and other gains (losses)	$ 27.3	$ 0

Net Income (Loss) Per Common _3

Net Income (Loss) Per Common Share - Net Income (Loss) Per Common Share on Basic and Diluted Basis (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net income (loss)	$ (1)	$ 29.8
Less: Preferred share dividends	2.6	2.6
Net income (loss) attributable to common shareholders	(3.6)	27.2
Net income (loss) attributable to common shareholders	$ (3.6)	$ 27.2
Weighted average common shares outstanding - basic (in shares)	34,891,935	34,712,650
Effect of dilutive securities:
Equity compensation awards (in shares)	0	225,363
Weighted average common shares outstanding - diluted (in shares)	34,891,935	34,938,013
Net income (loss) per common share:
Basic (in dollars per share)	$ (0.11)	$ 0.78
Diluted (in dollars per share)	$ (0.11)	$ 0.78

Net Income (Loss) Per Common _4

Net Income (Loss) Per Common Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Earnings Per Share [Abstract]
Treasury shares (in shares)	11,315,889	11,315,889	11,315,889
Equity compensation awards with anti-dilutive effect (in shares)	173,541	0

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Schedule of Interest Paid and Income Taxes Paid (Recovered) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Supplemental Cash Flow [Line Items]
Total interest paid	$ 5.6	$ 5.6
Income taxes paid	0.3	0.9
Income taxes recovered	(0.2)	(0.1)
Income taxes paid, net	0.1	0.8
Senior unsecured fixed rate notes
Supplemental Cash Flow [Line Items]
Total interest paid	2.3	2.3
Junior subordinated debentures
Supplemental Cash Flow [Line Items]
Total interest paid	2.5	2.5
Other indebtedness
Supplemental Cash Flow [Line Items]
Total interest paid	$ 0.8	$ 0.8

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2019	Mar. 31, 2022	Mar. 31, 2021
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense		$ 2.2	$ 1.5
Employee service share-based compensation, unrecognized compensation costs on non-vested awards		$ 18
Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		1 year
Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		4 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense		$ 0.5	$ 0.7
Employee service share-based compensation, unrecognized compensation costs on non-vested awards		$ 8.5
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		3 years
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period, years		4 years
2019 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized (in shares)	1,885,000
Expiration period	10 years

Share-based Compensation - Summ

Share-based Compensation - Summary of Restricted Share Activity (Detail) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Shares
Outstanding, beginning balance (in shares) | shares	278,430
Granted (in shares) | shares	240,677
Reclassed from performance shares (in shares) | shares	14,373
Vested and issued (in shares) | shares	(83,101)
Expired or forfeited (in shares) | shares	(13,379)
Outstanding, ending balance (in shares) | shares	437,000
Weighted-Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 49.57
Granted (in dollars per share) | $ / shares	41
Reclassed from performance shares (in dollars per share) | $ / shares	32.61
Vested and issued (in dollars per share) | $ / shares	46.32
Expired or forfeited (in dollars per share) | $ / shares	48.72
Outstanding, ending balance (in dollars per share) | $ / shares	$ 44.58

Share-based Compensation - Su_2

Share-based Compensation - Summary of Performance Shares Activity (Details)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Weighted-Average Grant Date Fair Value
Reclassed to restricted shares (in dollars per share) | $ / shares	$ 32.61
Performance Shares
Shares
Outstanding, beginning balance (in shares) | shares	200,564
Granted (in shares) | shares	125,074
Reclassed to restricted shares (in shares) | shares	(14,373)
Vested and issued (in shares) | shares	(1,831)
Expired or forfeited (in shares) | shares	(17,398)
Outstanding, ending balance (in shares) | shares	292,036
Weighted-Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 47.52
Granted (in dollars per share) | $ / shares	41
Vested and issued (in dollars per share) | $ / shares	68.27
Expired or forfeited (in dollars per share) | $ / shares	59.03
Outstanding, ending balance (in dollars per share) | $ / shares	$ 44.64

Underwriting, Acquisition and_3

Underwriting, Acquisition and Insurance Expenses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Underwriting, Acquisition and Insurance Expenses [Abstract]
Commissions	$ 77.9	$ 76.5
Other underwriting and insurance expenses	103.2	106.6
Underwriting, acquisition and insurance expenses, total	181.1	183.1
Net deferral of policy acquisition costs	(8.2)	(6.7)
Total underwriting, acquisition and insurance expenses	$ 172.9	$ 176.4

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Net operating losses carryback period	2 years
Capital losses carryback period	3 years
Change in valuation allowance	$ (1.8)	$ (0.8)
Change in uncertain tax position liability	0.1	$ (2.4)
Interest on income taxes expense	$ 0.1

Income Taxes - Schedule of Pre-

Income Taxes - Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 12	$ 31.2
Effective Tax Rate	109.70%	4.30%
Bermuda
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (0.2)	$ 5
Effective Tax Rate	0.00%	0.00%
United States
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 38.8	$ 41.3
Effective Tax Rate	21.90%	15.70%
United Kingdom
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 5	$ (18.3)
Effective Tax Rate	80.80%	28.10%
Brazil
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (0.1)	$ 1.6
Effective Tax Rate	(422.40%)	0.00%
United Arab Emirates
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.6	$ 0.3
Effective Tax Rate	0.00%	0.00%
Ireland
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (33.3)	$ (0.1)
Effective Tax Rate	0.00%	0.00%
Italy
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.1	$ 0.9
Effective Tax Rate	138.10%	0.00%
Malta
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 1.1	$ 0.5
Effective Tax Rate	0.00%	0.00%

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income tax provision at expected rate	$ 9.4	$ 6.3
Tax effect of:
Nontaxable investment income	(0.1)	(0.2)
Foreign exchange adjustments	0.1	(0.2)
Sale of Brazil Operations	1.6	0
Change in uncertain tax position liability	0.1	(2.4)
Change in valuation allowance	(1.8)	(0.8)
Impact of change in tax rate related to Finance Act 2021	0.5	0
Lease termination	2	0
Other	1.2	(1.3)
Income tax provision	$ 13	$ 1.4

Commitments and Contingencies (

Commitments and Contingencies (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments related to its limited partnership investments (up to)	$ 68.8
Contractual commitments period (not to exceed)	12 years

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)segment	Dec. 31, 2021USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	2
Assets associated with trade capital providers | $	$ 247	$ 825.9

Segment Information - Revenue a

Segment Information - Revenue and Income (Loss) Before Income Taxes for Each Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Earned premiums	$ 480.6	$ 466.1
Net investment income	37.7	44.4
Net realized investment and other gains (losses)	(34.5)	13.1
Total revenue	483.8	523.6
(Loss) income before income taxes	12	31.2
Foreign currency exchange losses	(2.9)	(1.3)
Operating Segments
Segment Reporting Information [Line Items]
(Loss) income before income taxes	65.6	25.4
Corporate and Other
Segment Reporting Information [Line Items]
Net investment income	0	2.8
(Loss) income before income taxes	(16.2)	(6)
U.S. Operations | Operating Segments
Segment Reporting Information [Line Items]
Earned premiums	336.4	314.4
Net investment income	25.6	28.8
(Loss) income before income taxes	43.9	36.6
International Operations | Operating Segments
Segment Reporting Information [Line Items]
Earned premiums	144.2	151.5
Net investment income	11.4	12
(Loss) income before income taxes	22.7	(11.8)
Run-off Lines | Operating Segments
Segment Reporting Information [Line Items]
Earned premiums	0	0.2
Net investment income	0.7	0.8
(Loss) income before income taxes	$ (1)	$ 0.6

Segment Information - Schedule

Segment Information - Schedule of Earned Premiums by Geographic Location (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 480.6	$ 466.1
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	336.4	312.8
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	127.1	99
Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	6.4	25.1
Malta
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	2.3	14
All other jurisdictions
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 8.4	$ 15.2

Segment Information - Identifia

Segment Information - Identifiable Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 9,981	$ 10,317.8
Operating Segments | U.S. Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	5,716.2	5,800.1
Operating Segments | International Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	3,780.9	3,932.3
Operating Segments | Run-off Lines
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	305.3	314.7
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 178.6	$ 270.7