Employers (EIG) 10-Q 27 Oct 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 24, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-33245
Entity Registrant Name	EMPLOYERS HOLDINGS, INC.
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	04-3850065
Entity Address, Address Line One	2340 Corporate Circle, Suite 200
Entity Address, City or Town	Henderson,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89074
City Area Code	888
Local Phone Number	682-6671
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	EIG
Security Exchange Name	NYSE
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		25,720,677
Entity Central Index Key	0001379041
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investments:
Fixed maturity securities at fair value (amortized cost $2,198.6 at September 30, 2023 and $2,366.7 at December 31, 2022, less CECL allowance of $3.2 at September 30, 2023 and $4.5 at December 31, 2022)	$ 1,997.2	$ 2,186.3
Equity securities at fair value (cost $126.3 at September 30, 2023 and $144.2 at December 31, 2022)	193	197
Equity securities at cost	6	6.7
Other invested assets (cost $81.1 at September 30, 2023 and $54.4 at December 31, 2022)	90.9	59.7
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	46.8	119.1
Total investments	2,333.9	2,568.8
Cash and cash equivalents	108.8	89.2
Restricted Cash and Cash Equivalents	0.2	0.2
Accrued investment income	18.5	19
Premiums receivable (less CECL allowance of $16.2 at September 30, 2023 and $12.8 at December 31, 2022)	363.3	305.9
Reinsurance recoverable for:
Paid losses	11.5	6.8
Unpaid losses (less CECL allowance of $0.9 at September 30, 2023 and $0.9 at December 31, 2022)	425.7	444.5
Deferred policy acquisition costs	57.1	48.3
Deferred income tax asset, net	64.2	62.7
Property and equipment, net	7	12
Operating lease right-of-use assets	4.3	11.5
Intangible assets, net	13.6	13.6
Goodwill	36.2	36.2
Contingent commission receivable—LPT Agreement	13.9	13.9
Cloud computing arrangements	33.2	42.9
Other assets	35.6	41.2
Total assets	3,527	3,716.7
Liabilities and stockholders’ equity
Unpaid losses and loss adjustment expenses	1,913.4	1,960.7
Unearned premiums	387	339.5
Commissions and premium taxes payable	62.8	58.2
Accounts payable and accrued expenses	22.3	28.7
Deferred reinsurance gain—LPT Agreement	100.2	106.1
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	40.4	182.5
Operating lease liability	5.1	13.6
Non-cancellable obligations	18.5	26.1
Other liabilities	58.3	57.1
Total liabilities	2,608	2,772.5
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 58,004,955 and 57,876,287 shares issued and 25,719,074 and 27,160,748 shares outstanding at September 30, 2023 and December 31, 2022, respectively	0.6	0.6
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	418.2	414.6
Retained earnings	1,346.1	1,295.6
Accumulated other comprehensive loss, net of tax	(156.6)	(138.9)
Treasury stock, at cost (32,285,881 shares at September 30, 2023 and 30,715,539 shares at December 31, 2022)	(689.3)	(627.7)
Total stockholders’ equity	919	944.2
Total liabilities and stockholders’ equity	$ 3,527	$ 3,716.7

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Available for sale:
Debt securities, available-for-sale, amortized cost	$ 2,198.6	$ 2,366.7
Debt Securities, Available-for-sale, Allowance for Credit Loss	3.2	4.5
Equity Securities, FV-NI, Cost	126.3	144.2
Other Investments and Securities, at Cost	81.1	54.4
Available for sale, short-term investments, at amortized cost	46.8	119.1
Accounts Receivable, Allowance for Credit Loss, Current	16.2	12.8
Reinsurance recoverables on unpaid losses, allowance	$ 0.9	$ 0.9
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	58,004,955	57,876,287
Common stock, shares outstanding (in shares)	25,719,074	27,160,748
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	32,285,881	30,715,539

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues
Net premiums earned	$ 184.6	$ 178.7	$ 534.4	$ 494.1
Net investment income	25.9	23.7	80.3	62.8
Net realized and unrealized (losses) gains on investments	(7.1)	1.9	10.7	(65.5)
Other income (loss)	0.1	0.1	(0.2)	0.3
Total revenues	203.5	204.4	625.2	491.7
Expenses
Losses and loss adjustment expenses	114.9	112.3	312.8	299.7
Commission expense	26.7	25.3	73.8	69.9
Underwriting and general and administrative expenses	43.5	41.9	133.7	120.6
Interest and financing expenses	1	1.1	5.2	1.6
Other Expenses	0	0	9.4	0
Total expenses	186.1	180.6	534.9	491.8
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	17.4	23.8	90.3	(0.1)
Income tax expense (benefit)	3.4	4.7	17.8	(1.4)
Net Income	14	19.1	72.5	1.3
Comprehensive (loss) income
Unrealized AFS investment losses arising during the period, net of tax benefit of $7.3 and $16.0 for the three months ended September 30, 2023 and 2022, respectively, and $5.3 and $59.0 for the nine months ended September 30, 2023 and 2022, respectively	(27)	(60.3)	(20)	(222.2)
Reclassification adjustment for realized AFS investment losses (gains) in net income, net of tax (benefit) expense of $(0.3) and $1.1 for the three months ended September 30, 2023 and 2022, and $(0.6) and $(0.7) for the nine months ended September 30, 2023 and 2022, respectively	0.9	(3.9)	2.3	2.7
Other comprehensive loss, net of tax	(26.1)	(64.2)	(17.7)	(219.5)
Total Comprehensive (loss) income	$ (12.1)	$ (45.1)	$ 54.8	$ (218.2)
Earnings per common share (Note 13):
Basic	$ 0.54	$ 0.70	$ 2.72	$ 0.05
Diluted	0.54	0.70	2.71	0.05
Cash dividends declared per common share and eligible plan awards	$ 0.28	$ 0.26	$ 0.82	$ 1.77

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement Parenthetical [Abstract]
OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment, Tax	$ 7.3	$ 16	$ 5.3	$ 59
Other comprehensive income (loss), reclassification adjustment for sale of securities included in net income, tax	$ (0.3)	$ 1.1	$ (0.6)	$ (0.7)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders Equity Statement - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income, Net	Treasury Stock, Common
Stockholders' equity, shares at Dec. 31, 2021		57,690,254
Stockholders' equity, value at Dec. 31, 2021	$ 1,213.1	$ 0.6	$ 410.7	$ 1,338.5	$ 60.6	$ (597.3)
Stock-based obligations, shares		0
Stock-based obligations, value	$ 3.4	$ 0	3.4	0	0	0
Stock-options exercised, shares	41,665	41,665
Stock-options exercised, value	$ 1.1	$ 0	1.1	0	0	0
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, shares		139,598
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, value	(2.3)	$ 0	(2.3)	0	0	0
Acquisition of common stock, shares		0
Acquisition of common stock, value	(28.7)	$ 0	0	0	0	(28.7)
Dividends declared, shares		0
Dividends declared, value	(49.4)	$ 0	0	(49.4)	0	0
Net income	1.3	0	0	1.3	0	0
Change in net unrealized gains in investments, net of tax	(219.5)	$ 0	0	0	(219.5)	0
Stockholders' equity, shares at Sep. 30, 2022		57,871,517
Stockholders' equity, value at Sep. 30, 2022	919	$ 0.6	412.9	1,290.4	(158.9)	(626)
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	58.3
Stockholders' equity, shares at Dec. 31, 2021		57,690,254
Stockholders' equity, value at Dec. 31, 2021	$ 1,213.1	$ 0.6	410.7	1,338.5	60.6	(597.3)
Stock-options exercised, shares	41,665
Stockholders' equity, shares at Dec. 31, 2022	57,876,287	57,876,287
Stockholders' equity, value at Dec. 31, 2022	$ 944.2	$ 0.6	414.6	1,295.6	(138.9)	(627.7)
Stockholders' equity, shares at Jun. 30, 2022		57,871,517
Stockholders' equity, value at Jun. 30, 2022	977.5	$ 0.6	411.8	1,278.4	(94.7)	(618.6)
Stock-based obligations, shares		0
Stock-based obligations, value	1.1	$ 0	1.1	0	0	0
Acquisition of common stock, shares		0
Acquisition of common stock, value	(7.4)	$ 0	0		0	(7.4)
Dividends declared, shares		0
Dividends declared, value	(7.1)	$ 0	0	(7.1)	0	0
Net income	19.1	0	0	19.1	0	0
Change in net unrealized gains in investments, net of tax	(64.2)	$ 0	0	0	(64.2)	0
Stockholders' equity, shares at Sep. 30, 2022		57,871,517
Stockholders' equity, value at Sep. 30, 2022	919	$ 0.6	412.9	1,290.4	(158.9)	(626)
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	$ 17.1
Stockholders' equity, shares at Dec. 31, 2022	57,876,287	57,876,287
Stockholders' equity, value at Dec. 31, 2022	$ 944.2	$ 0.6	414.6	1,295.6	(138.9)	(627.7)
Stock-based obligations, shares		0
Stock-based obligations, value	$ 4.4	$ 0	4.4	0	0	0
Stock-options exercised, shares	23,500	23,500
Stock-options exercised, value	$ 0.7	$ 0	0.7	0	0	0
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, shares		105,168
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, value	(1.5)	$ 0	(1.5)	0	0	0
Acquisition of common stock, shares		0
Acquisition of common stock, value	(61.6)	$ 0	0	0	0	(61.6)
Dividends declared, shares		0
Dividends declared, value	(22)	$ 0	0	(22)	0	0
Net income	72.5	0	0	72.5	0	0
Change in net unrealized gains in investments, net of tax	$ (17.7)	$ 0	0	0	(17.7)	0
Stockholders' equity, shares at Sep. 30, 2023	58,004,955	58,004,955
Stockholders' equity, value at Sep. 30, 2023	$ 919	$ 0.6	418.2	1,346.1	(156.6)	(689.3)
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	4.7
Stockholders' equity, shares at Jun. 30, 2023		57,997,485
Stockholders' equity, value at Jun. 30, 2023	951.7	$ 0.6	417.1	1,339.4	(130.5)	(674.9)
Stock-based obligations, shares		0
Stock-based obligations, value	1.3	$ 0	1.3	0	0	0
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, shares		7,470
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, value	(0.2)	$ 0	(0.2)	0	0	0
Acquisition of common stock, shares		0
Acquisition of common stock, value	(14.4)	$ 0	0	0	0	(14.4)
Dividends declared, shares		0
Dividends declared, value	(7.3)	$ 0	0	(7.3)	0	0
Net income	14	0	0	14	0	0
Change in net unrealized gains in investments, net of tax	$ (26.1)	$ 0	0	0	(26.1)	0
Stockholders' equity, shares at Sep. 30, 2023	58,004,955	58,004,955
Stockholders' equity, value at Sep. 30, 2023	$ 919	$ 0.6	$ 418.2	$ 1,346.1	$ (156.6)	$ (689.3)
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	$ 7

Consolidated Statements of St_2

Consolidated Statements of Stockholders Equity (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Stockholders' Equity [Abstract]
Change in net unrealized (losses) gains on investments, net of tax	$ 7	$ 17.1	$ 4.7	$ 58.3

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Operating activities
Net income	$ 14	$ 19.1	$ 72.5	$ 1.3
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			3.7	4.1
Stock-based compensation			4.5	3.4
Amortization of cloud computing arrangements	4.2		12.6	12.1	$ 16.4
Amortization of premium on investments, net			2.4	2.6
Allowance for expected credit losses			3.4	0.7
Deferred income tax expense (benefit)			3.2	(20.6)
Net realized and unrealized (gains) losses on investments			(10.7)	65.5
Asset Impairment Charges			2.6	0
Gain (Loss) on Termination of Lease			(1)	0
Change in operating assets and liabilities:
Premiums receivable			(60.8)	(57)
Reinsurance recoverable on paid and unpaid losses			14.1	20.7
Cloud computing arrangements			(2.9)	(15.1)
Operating lease right-of-use assets			7.2	2
Current federal income taxes			(10.6)	6.8
Unpaid losses and loss adjustment expenses			(47.3)	(1.3)
Unearned premiums			47.5	41.1
Accounts payable, accrued expenses and other liabilities			(0.8)	(0.1)
Deferred reinsurance gain—LPT Agreement			(5.9)	(6.3)
Operating lease liabilities			(7.5)	(2.3)
Non-cancellable obligations			(7.6)	6.1
Other			3.2	3.8
Net cash provided by operating activities			21.8	67.5
Investing activities
Purchases of fixed maturity securities			(290.2)	(540)
Payments to Acquire Equity Securities, FV-NI			(31.4)	(111.4)
Purchases of short-term investments			(57.7)	(9.6)
Purchases of other invested assets			(26.7)	(18.8)
Proceeds from sale of fixed maturity securities	204	30.6	329.5	230.7
Proceeds from Sale of Equity Securities, FV-NI			45.2	204
Proceeds from maturities and redemptions of fixed maturity securities			119.9	133.2
Proceeds from maturities of short-term investments			132.3	20
Net change in unsettled investment purchases and sales			5.6	(3.6)
Capital expenditures and other			(1.5)	(2.2)
Net cash provided by (used in) investing activities			225	(97.7)
Financing activities
Acquisition of common stock			(61.5)	(28.7)
Cash transactions related to stock-based compensation			(0.9)	(1.2)
Dividends paid to stockholders			(22.5)	(49.3)
Proceeds from FHLBank Borrowings, Financing Activities			0	182.5
Repayments of FHLBank Advance, Investing Activities			(142.1)	0
Proceeds from Lines of Credit			0	10
Repayments on line of credit advances			0	(10)
Financing cash flows from finance leases			(0.2)	(0.1)
Net cash (used in) provided by financing activities			(227.2)	103.2
Net increase in cash, cash equivalents and restricted cash			19.6	73
Cash, cash equivalents, restricted cash and restricted cash equivalents at the beginning of the period			89.4	75.3	75.3
Cash, cash equivalents, restricted cash and restricted cash equivalents at the end of the period	109	148.3	109	148.3	89.4
Cash and cash equivalents	108.8		108.8		89.2
Restricted Cash and Cash Equivalents	0.2		0.2		0.2
Total cash, cash equivalents, restricted cash	$ 109	$ 148.3	$ 109	$ 148.3	$ 89.4

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Description and Basis of Presentation	Basis of Presentation and Summary of Operations Employers Holdings, Inc. (EHI) is a Nevada holding company. Through its wholly owned insurance subsidiaries, Employers Insurance Company of Nevada (EICN), Employers Compensation Insurance Company (ECIC), Employers Preferred Insurance Company (EPIC), Employers Assurance Company (EAC), and Cerity Insurance Company (CIC), EHI is engaged in the commercial property and casualty insurance industry, specializing in workers’ compensation products and services. Unless otherwise indicated, all references to the “Company” refer to EHI, together with its subsidiaries. In 1999, the Nevada State Industrial Insurance System (the Fund) entered into a retroactive 100% quota share reinsurance agreement (the LPT Agreement) through a loss portfolio transfer transaction with third party reinsurers. The LPT Agreement commenced on June 30, 1999 and will remain in effect until: (i) all claims under the covered policies have closed; (ii) the LPT Agreement is commuted or terminated, upon the mutual agreement of the parties; or (iii) the reinsurers’ aggregate maximum limit of liability is exhausted, whichever occurs first. The LPT Agreement does not provide for any additional termination terms. On January 1, 2000, EICN assumed all of the assets, liabilities and operations of the Fund, including the Fund’s rights and obligations associated with the LPT Agreement (See Note 9). The Company accounts for the LPT Agreement as retroactive reinsurance. Upon entry into the LPT Agreement, an initial deferred reinsurance gain (the Deferred Gain) was recorded as a liability on the Company’s Consolidated Balance Sheets. The Company is entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is estimated based on both actual paid results to date and projections of expected paid losses under the LPT Agreement and is recorded as an asset on the Company’s Consolidated Balance Sheets. The accompanying consolidated financial statements have been prepared in accordance with United States (U.S.) generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities Exchange Act of 1934, as amended. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal, recurring adjustments) necessary for a fair presentation of the Company’s consolidated financial position and results of operations for the periods presented have been included. The results of operations for an interim period are not necessarily indicative of the results for an entire year. These financial statements have been prepared consistent with the accounting policies described in the Company’s Form 10-K for the year ended December 31, 2022 (Annual Report). The Company operates through two reportable segments: Employers and Cerity . Each of the segments represents a separate and distinct underwriting platform through which the Company conducts insurance business. This presentation allows the reader, as well as the Company's chief operating decision makers, to objectively analyze the business originated through each of these channels. Detailed financial information about the Company's operating segments is presented in Note 14. Use of Estimates The preparation of the consolidated 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 consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. As a result, actual results could differ from these estimates. The most significant areas that require management judgment are the estimate of unpaid losses and loss adjustment expenses (LAE), evaluation of reinsurance recoverables, recognition of premium revenue, recoverability of deferred income taxes, and valuation of investments.

New Accounting Standards

New Accounting Standards	9 Months Ended
	Sep. 30, 2023
New Accounting Standards [Abstract]
New Accounting Standards	New Accounting Standards Recently Issued Accounting Standards None. Recently Adopted Accounting Standards In March 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2020-04, Reference Rate Reform (Topic 848) . This update provided optional transition guidance to ease the potential accounting burden associated with transitioning away from the London Interbank Offered Rate (LIBOR), with optional expedients and exceptions related to the application of US GAAP to contracts, hedging relationships and other transactions affected by reference rate reform. Companies can elect to adopt this ASU through December 31, 2024. The Company determined that there was no impact of LIBOR transitioning on its existing contracts and investments.

Valuation of Financial Instrume

Valuation of Financial Instruments	9 Months Ended
	Sep. 30, 2023
Fair Value of Financial Instruments [Abstract]
Fair Value of Financial Instruments	Valuation of Financial Instruments Financial Instruments Carried at Fair Value The carrying value and the estimated fair value of the Company’s financial instruments at fair value were as follows: September 30, 2023 December 31, 2022 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Financial assets Total investments at fair value $ 2,237.0 $ 2,237.0 $ 2,502.4 $ 2,502.4 Cash and cash equivalents 108.8 108.8 89.2 89.2 Restricted cash and cash equivalents 0.2 0.2 0.2 0.2 Assets and liabilities recorded at fair value on the Company’s Consolidated Balance Sheets are categorized based upon the levels of judgment associated with the inputs used to measure their fair value. Level inputs are defined as follows: • Level 1 - Inputs are unadjusted quoted market prices for identical assets or liabilities in active markets at the measurement date. • Level 2 - Inputs other than Level 1 prices that are observable for similar assets or liabilities through corroboration with market data at the measurement date. • Level 3 - Inputs that are unobservable that reflect management’s best estimate of what willing market participants would use in pricing the assets or liabilities at the measurement date. The Company uses third party pricing services to assist with its investment accounting function. The ultimate pricing source varies depending on the investment security and pricing service used, but investment securities valued on the basis of observable inputs (Levels 1 and 2) are generally assigned values on the basis of actual transactions. Securities valued on the basis of pricing models with significant unobservable inputs or non-binding broker quotes are classified as Level 3. The Company performs quarterly analyses on the prices it receives from third parties to determine whether the prices are reasonable estimates of fair value, including confirming the fair values of these securities through observable market prices using an alternative pricing source, as it is ultimately management’s responsibility to ensure that the fair values reflected in the Company’s consolidated financial statements are appropriate. If differences are noted in these analyses, the Company may obtain additional information from other pricing services to validate the quoted price. The Company bases all of its estimates of fair value for assets on the bid prices, when available, as they represent what a third-party market participant would be willing to pay in an arm’s length transaction. For securities not actively traded, third party pricing services may use quoted market prices of similar instruments or discounted cash flow analyses, incorporating inputs that are currently observable in the markets for similar securities. Inputs that are often used in the valuation methodologies include, but are not limited to, broker quotes, benchmark yields, credit spreads, default rates, and prepayment speed assumptions. There were no material adjustments to the valuation methodology utilized by third party pricing services as of September 30, 2023 and December 31, 2022. These methods of valuation only produce an estimate of fair value if there is objectively verifiable information to produce a valuation. If objectively verifiable information is not available, the Company would be required to produce an estimate of fair value using some of the same methodologies, making assumptions for market-based inputs that are unavailable. As of September 30, 2023, the Company held $32.3 million of fixed maturity securities at fair value that were designated Level 3. These private placement securities were designated as Level 3 securities d ue to the limited amount of observable market information available. The following table presents the Company’s investments at fair value and the corresponding fair value measurements. September 30, 2023 December 31, 2022 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (in millions) Fixed maturity securities: U.S. Treasuries $ — $ 94.1 $ — $ — $ 90.8 $ — U.S. Agencies — 2.1 — — 2.1 — States and municipalities — 228.2 — — 317.6 — Corporate securities — 896.0 21.9 — 851.9 16.2 Residential mortgage-backed securities — 343.3 — — 360.2 — Commercial mortgage-backed securities — 56.8 — — 55.1 — Asset-backed securities — 96.4 10.4 — 58.1 8.0 Collateralized loan obligations — 126.6 — — 260.9 — Foreign government securities — 9.3 — — 10.2 — Other securities — 112.1 — — 155.2 — Total fixed maturity securities $ — $ 1,964.9 $ 32.3 $ — $ 2,162.1 $ 24.2 Equity securities at fair value: Industrial and miscellaneous $ 166.6 $ — $ — $ 165.3 $ — $ — Other 26.4 — — 31.7 — — Total equity securities at fair value $ 193.0 $ — $ — $ 197.0 $ — $ — Short-term investments $ 33.3 $ 13.5 $ — $ 119.1 $ — $ — Total investments at fair value $ 226.3 $ 1,978.4 $ 32.3 $ 316.1 $ 2,162.1 $ 24.2 Financial Instruments Carried at Cost All of the Company's insurance subsidiaries are members of the Federal Home Loan Bank of San Francisco (FHLB). Members are required to purchase stock in the FHLB in addition to maintaining collateral deposits that back any funds advanced and standby letters of credit issued (See Note 10). The Company’s investment in FHLB stock is recorded at cost, which approximates fair value, as purchases and sales of these securities are at par value with the issuer. FHLB stock is considered a restricted security and is periodically evaluated by the Company for impairment based on the estimated ultimate recovery of par value. Financial Instruments Carried at Net Asset Value The Company has investments in private equity limited partnership interests that are included in Other invested assets on the Company’s Consolidated Balance Sheets. These investments do not have readily determinable fair values and are carried at net asset value (NAV) and therefore are excluded from the fair value hierarchy. The Company initially estimates the value of these investments using the transaction price. In subsequent periods, the Company measures these investments using NAV per share provided quarterly by the general partner, based on financial statements that are audited annually. These investments are generally not redeemable by the investees and cannot be sold without approval of the general partner. These investments have fund terms of 3 to 12 years, subject to two or three one Additionally, certain cash equivalents, principally money market securities, are measured using NAV, which approximates fair value. The following table presents cash and investments carried at NAV on the Company’s Consolidated Balance Sheets. September 30, 2023 December 31, 2022 (in millions) Cash equivalents carried at NAV $ 99.7 $ 65.5 Other invested assets carried at NAV 90.9 59.7 The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the nine months ended September 30, 2023. Level 3 Securities (in millions) Beginning balance, January 1, 2023 $ 24.2 Purchases 8.7 Unrealized losses included in comprehensive income or loss (0.6) Ending balance, September 30, 2023 $ 32.3

Investments

Investments	9 Months Ended
	Sep. 30, 2023
Investments [Abstract]
Investments	Investments The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s available-for-sale (AFS) investments were as follows: Amortized Allowance for Current Expected Credit Losses Gross Gross Estimated (in millions) At September 30, 2023 Fixed maturity securities U.S. Treasuries $ 98.9 $ — $ — $ (4.8) $ 94.1 U.S. Agencies 2.2 — — (0.1) 2.1 States and municipalities 240.8 — 0.1 (12.7) 228.2 Corporate securities 1,023.9 (2.6) 1.3 (104.7) 917.9 Residential mortgage-backed securities 401.3 — — (58.0) 343.3 Commercial mortgage-backed securities 64.5 — — (7.7) 56.8 Asset-backed securities 113.6 — 0.1 (6.9) 106.8 Collateralized loan obligations 127.8 — — (1.2) 126.6 Foreign government securities 12.7 — — (3.4) 9.3 Other securities (1) 112.9 (0.6) 0.7 (0.9) 112.1 Total fixed maturity securities $ 2,198.6 $ (3.2) $ 2.2 $ (200.4) $ 1,997.2 Short-term investments 46.8 — — — 46.8 Total AFS investments $ 2,245.4 $ (3.2) $ 2.2 $ (200.4) $ 2,044.0 At December 31, 2022 Fixed maturity securities U.S. Treasuries $ 95.1 $ — $ 0.1 $ (4.4) $ 90.8 U.S. Agencies 2.2 — — (0.1) 2.1 States and municipalities 326.7 — 0.8 (9.9) 317.6 Corporate securities 963.4 (2.8) 2.0 (94.5) 868.1 Residential mortgage-backed securities 403.5 — 0.3 (43.6) 360.2 Commercial mortgage-backed securities 61.5 — — (6.4) 55.1 Asset-backed securities 74.0 — 0.1 (8.0) 66.1 Collateralized loan obligations 268.1 — — (7.2) 260.9 Foreign government securities 13.0 — — (2.8) 10.2 Other securities (1) 159.2 (1.7) 0.6 (2.9) 155.2 Total fixed maturity securities $ 2,366.7 $ (4.5) $ 3.9 $ (179.8) $ 2,186.3 Short-term investments 119.1 — — — 119.1 Total AFS investments $ 2,485.8 $ (4.5) $ 3.9 $ (179.8) $ 2,305.4 (1) Other securities within fixed maturity securities consist of bank loans, which are classified as AFS and reported at fair value. The cost and estimated fair value of the Company’s equity securities recorded at fair value at September 30, 2023 and December 31, 2022 were as follows: Cost Estimated Fair Value (in millions) At September 30, 2023 Equity securities at fair value Industrial and miscellaneous $ 104.4 $ 166.6 Other 21.9 26.4 Total equity securities at fair value $ 126.3 $ 193.0 At December 31, 2022 Equity securities at fair value Industrial and miscellaneous $ 115.3 $ 165.3 Other 28.9 31.7 Total equity securities at fair value $ 144.2 $ 197.0 The Company had Other invested assets totaling $90.9 million and $59.7 million (initial cost of $81.1 million and $54.4 million) at September 30, 2023 and December 31, 2022, respectively, consisting of private equity limited partnerships, which are carried at NAV based on information provided by the general partner. These investments are non-redeemable until conversion and are periodically evaluated by the Company for impairment based on the ultimate recovery of the investment. Changes in the value of these investments are recorded through Net realized and unrealized gains and losses on the Company’s Consolidated Statements of Comprehensive Income (Loss). The amortized cost and estimated fair value of the Company’s fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Expected maturities differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Cost Estimated Fair Value (in millions) Due in one year or less $ 87.3 $ 85.9 Due after one year through five years 716.0 677.7 Due after five years through ten years 601.0 527.0 Due after ten years 87.1 73.1 Mortgage and asset-backed securities 707.2 633.5 Total $ 2,198.6 $ 1,997.2 The following is a summary of AFS investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 months or greater in each case as of September 30, 2023 and December 31, 2022. September 30, 2023 December 31, 2022 Estimated Fair Value Gross Number of Issues Estimated Fair Value Gross Number of Issues (dollars in millions) Less than 12 months: Fixed maturity securities U.S. Treasuries $ 29.6 $ (0.6) 12 $ 76.8 $ (3.5) 13 U.S. Agencies — — — 2.1 (0.1) 1 States and municipalities 122.3 (4.0) 44 193.4 (9.0) 68 Corporate securities 133.1 (5.4) 42 763.3 (76.4) 335 Residential mortgage-backed securities 42.3 (1.3) 43 236.8 (17.9) 186 Commercial mortgage-backed securities — — — 52.5 (5.7) 22 Asset-backed securities 46.7 (0.5) 24 27.6 (2.6) 22 Collateralized loan obligations — — — 209.9 (5.5) 37 Other securities 18.7 (0.3) 88 81.6 (1.8) 224 Total fixed maturity securities 392.7 (12.1) 253 1,644.0 (122.5) 908 Total less than 12 months $ 392.7 $ (12.1) 253 $ 1,644.0 $ (122.5) 908 12 months or greater: Fixed maturity securities U.S. Treasuries $ 63.8 $ (4.2) 11 $ 11.2 $ (0.9) 4 US Agencies 2.1 (0.1) 1 — — — States and municipalities 95.7 (8.7) 40 5.4 (0.9) 3 Corporate securities 770.9 (99.3) 369 84.6 (18.1) 84 Residential mortgage-backed securities 295.1 (56.7) 225 106.6 (25.7) 65 Commercial mortgage-backed securities 51.8 (7.7) 24 2.6 (0.7) 3 Asset-backed securities 49.1 (6.4) 31 27.7 (5.4) 11 Collateralized loan obligations 121.6 (1.2) 28 36.9 (1.7) 11 Foreign government securities 9.3 (3.4) 2 10.2 (2.8) 3 Other securities 20.8 (0.6) 99 38.4 (1.1) 119 Total fixed maturity securities 1,480.2 (188.3) 830 323.6 (57.3) 303 Total 12 months or greater $ 1,480.2 $ (188.3) 830 $ 323.6 $ (57.3) 303 As of September 30, 2023 and December 31, 2022, the Company had an allowance for current expected credit losses (CECL) on AFS debt securities of $3.2 million and $4.5 million, respectively (See Note 5). Those fixed maturity securities whose total fair value was less than amortized cost at each of September 30, 2023 and December 31, 2022, were those in which the Company had no intent, need or requirement to sell at an amount less than their amortized cost. Realized gains and losses on investments include the gain or loss on a security at the time of sale compared to its original or adjusted cost (equity securities and other invested assets) or amortized cost (fixed maturity securities). Realized losses on fixed maturity securities are also recognized when securities are written down as a result of an other-than-temporary impairment or for changes in CECL. Net realized gains and losses on investments and the change in unrealized gains and losses on the Company’s investments recorded at fair value are determined on a specific-identification basis and were as follows: Gross Realized Gains Gross Realized Losses Net Decrease (Increase) in CECL Allowance Change in Net Unrealized Gains (Losses) Changes in Fair Value Reflected in Earnings Changes in Fair Value Reflected in AOCI (1) , before tax (in millions) Three Months Ended September 30, 2023 Fixed maturity securities 0.3 $ (2.6) $ 1.1 $ (33.1) $ (1.2) $ (33.1) Equity securities — (1.5) — (5.8) (7.3) — Other invested assets — — — 1.4 1.4 — Total investments $ 0.3 $ (4.1) $ 1.1 $ (37.5) $ (7.1) $ (33.1) Nine Months Ended September 30, 2023 Fixed maturity securities $ 1.0 $ (5.2) $ 1.3 $ (22.4) $ (2.9) $ (22.4) Equity securities 0.1 (4.9) — 13.9 9.1 — Other invested assets — — — 4.5 4.5 — Total investments $ 1.1 $ (10.1) $ 1.3 $ (4.0) $ 10.7 $ (22.4) Three Months Ended September 30, 2022 Fixed maturity securities $ 0.1 $ (0.3) $ 5.2 $ (81.3) $ 5.0 $ (81.3) Equity securities 19.4 (5.1) — (16.6) (2.3) — Other invested assets — — — (0.8) (0.8) — Total investments $ 19.5 $ (5.4) $ 5.2 $ (98.7) $ 1.9 $ (81.3) Nine Months Ended September 30, 2022 Fixed maturity securities $ 2.5 $ (1.4) $ (4.5) $ (277.8) $ (3.4) $ (277.8) Equity securities 41.1 (14.0) — (90.4) (63.3) — Other invested assets — — — 1.2 1.2 — Total investments $ 43.6 $ (15.4) $ (4.5) $ (367.0) $ (65.5) $ (277.8) (1) AOCI means Accumulated other comprehensive income or loss Proceeds from the sales of fixed maturity securities were $204.0 million and $329.5 million for the three and nine months ended September 30, 2023, respectively, compared to $30.6 million and $230.7 million for the three and nine months ended September 30, 2022, respectively. Net investment income was as follows: Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Fixed maturity securities $ 22.6 $ 20.9 $ 69.7 $ 57.5 Equity securities 1.6 2.1 5.2 6.6 Other invested assets 1.1 0.9 2.9 1.8 Short-term investments 0.4 — 2.1 — Cash equivalents and restricted cash 1.4 0.7 3.2 0.8 Gross investment income 27.1 24.6 83.1 66.7 Investment expenses (1.2) (0.9) (2.8) (3.9) Net investment income $ 25.9 $ 23.7 $ 80.3 $ 62.8 The Company is required by various state laws and regulations to support, through securities on deposit or otherwise, its outstanding loss reserves in certain states in which it does business. These laws and regulations govern not only the amount but also the types of securities that are eligible for deposit. As of September 30, 2023 and December 31, 2022, securities having a

Current Expected Credit Losses

Current Expected Credit Losses	9 Months Ended
	Sep. 30, 2023
Credit Loss [Abstract]
Credit Losses	Current Expected Credit Losses Premiums Receivable Premiums receivable balances are all due within one year. The Company currently determines the allowance for premiums receivable based on an internal aging schedule using collectability and historical payment patterns, as well as current and expected future market conditions to determine the appropriateness of the allowance. Historical payment patterns and future market conditions provide the basis for the estimation along with similar risk characteristics and the Company's business strategy, which have not changed significantly over time. Changes in the allowance for CECL are recorded through underwriting and general and administrative expenses. The table below shows the changes in CECL on premiums receivable. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on premiums receivable $ 15.2 $ 9.7 $ 12.8 $ 10.3 Net change in CECL provision 3.7 2.8 10.9 6.6 Write-offs charged against CECL (0.7) (0.1) (1.9) (1.9) Recoveries collected (2.0) (1.4) (5.6) (4.0) Ending balance of CECL on premiums receivable $ 16.2 $ 11.0 $ 16.2 $ 11.0 Reinsurance Recoverable In assessing an allowance for reinsurance assets, which includes reinsurance recoverables and contingent commission receivables, the Company considers historical information, financial strength of reinsurers, collateralization amounts, and ratings to determine the appropriateness of the allowance. Historically, the Company has not experienced a credit loss from reinsurance transactions. In assessing future default, the Company evaluated the allowance for CECL under the ratings-based method using A.M. Best's Average Cumulative Net Impairment Rates. Reinsurer ratings are also assessed through this process. Changes in CECL are recorded through underwriting and general and administrative expenses. The table below shows the changes in CECL on reinsurance recoverables. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on reinsurance recoverables $ 0.9 $ 0.6 $ 0.9 $ 0.6 Net change in CECL provision — — — — Ending balance of CECL on reinsurance recoverables $ 0.9 $ 0.6 $ 0.9 $ 0.6 Investments The Company assesses all AFS debt securities in an unrealized loss position for CECL. The Company first assesses whether it intends to sell, or it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria is met, the security's amortized cost basis is written down to its fair value. For AFS debt securities that do not meet either criteria, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, management considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. Any impairment that has not been recorded through an allowance for CECL is recognized in Accumulated other comprehensive loss on the Company's Consolidated Balance Sheets. Changes in CECL are recorded through realized capital losses. As of September 30, 2023, the Company established an aggregate allowance for CECL in the amount of $3.2 million. For the Company’s investments in fixed-income debt securities, the allowance for CECL was determined by: (i) observing the credit characteristics of those debt securities that may have demonstrated a credit loss as of that date and by comparing the present value of cash flows expected to be collected to its amortized cost basis; and (ii) observing the credit characteristics of those debt securities that are expected to demonstrate a credit loss in the future by comparing the present value of cash flows expected to be collected to its amortized cost basis. The expected present value of cash flows are calculated using scenario based credit loss models derived from the discounted cash flows under the Comprehensive Capital Analysis Review framework, which is adopted by the Federal Reserve. As of September 30, 2023, the Company did not intend to sell any of its AFS debt securities in which its amortized cost exceeded its fair value. Accrued interest receivable on AFS debt securities totaled $18.5 million at September 30, 2023 and is excluded from the estimate of CECL based on historically timely payments. The table below shows the changes in the allowance for CECL on available-for-sale securities. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on AFS securities $ 4.3 $ 10.0 $ 4.5 $ 0.2 Net change in CECL provision (0.2) (5.2) 0.2 4.7 Reductions in allowance from disposals (0.9) — (1.5) — Recoveries of amounts previously written off — (0.1) — (0.2) Ending balance of CECL on AFS securities $ 3.2 $ 4.7 $ 3.2 $ 4.7

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	Property and Equipment Property and equipment consists of the following: As of September 30, As of December 31, 2023 2022 (in millions) Furniture and equipment $ 1.8 $ 3.3 Leasehold improvements 0.6 5.0 Computers and software 44.9 47.6 Automobiles 0.7 0.8 Property and equipment, gross 48.0 56.7 Accumulated depreciation (41.0) (44.7) Property and equipment, net $ 7.0 $ 12.0 Depreciation expenses related to property and equipment for the three and nine months ended September 30, 2023 were $1.0 million and $3.7 million, respectively, and $5.3 million for the year ended December 31, 2022. Internally developed software costs of $0.5 million and $1.2 million were capitalized during the three and nine months ended September 30, 2023, respectively, and $1.2 million in internally developed software costs were capitalized during the year ended December 31, 2022. Cloud Computing Arrangements The Company’s capitalized costs associated with cloud computing arrangements totaled $33.2 million and $42.9 million, which were comprised of service contract fees and implementation costs associated with hosting arrangements as of September 30, 2023 and December 31, 2022, respectively. Total amortization for hosting arrangements was $4.2 million and $12.6 million for the three and nine months ended September 30, 2023, respectively, and $16.4 million for the year ended December 31, 2022. Leases The Company determines if an arrangement is a lease at the inception of the transaction. Operating leases for offices are presented as a right-of-use asset (ROU asset) and lease liability on the Company’s Consolidated Balance Sheets. Financing leases for automobiles are included in property and equipment and other liabilities on the Company’s Consolidated Balance Sheets. ROU assets represent the right to use an underlying asset for the lease term and the lease liability represents the obligation to make lease payments arising from the lease transaction. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of the lease payments over the lease term. The Company uses collateralized incremental borrowing rates to determine the present value of lease payments. The ROU assets also include lease payments less any lease incentives within a lease agreement. The Company’s lease terms may include options to extend or terminate a lease. Lease expense for lease payments is recognized on a straight-line basis over the lease term. As of September 30, 2023, the Company’s operating leases have remaining terms of one Components of lease expense were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Operating lease expense $ 0.2 $ 0.9 $ 1.3 $ 2.6 Finance lease expense — 0.1 0.1 0.1 Total lease expense $ 0.2 $ 1.0 $ 1.4 $ 2.7 As of September 30, 2023 , the weighted average remaining lease term for o perating leases was 3.9 years and for finance leases was 2.1 years. The weighted average dis cou nt rate was 0.6% and 7.4% for operating and finance leases, respectively . Maturities of lease liabilities were as follows: As of September 30, 2023 Operating Leases Finance Leases (in millions) 2023 $ 0.4 $ — 2024 1.5 0.1 2025 1.3 0.1 2026 0.9 — 2027 0.9 — Thereafter 0.2 — Total lease payments 5.2 0.2 Less: imputed interest (0.1) — Total $ 5.1 $ 0.2 Supplemental balance sheet information related to leases was as follows: As of September 30, As of December 31, 2023 2022 (in millions) Operating leases: Operating lease right-of-use asset $ 4.3 $ 11.5 Operating lease liability 5.1 13.6 Finance leases: Property and equipment, gross 0.7 0.8 Accumulated depreciation (0.4) (0.4) Property and equipment, net 0.3 0.4 Other liabilities $ 0.2 $ 0.4 Supplemental cash flow information related to leases was as follows: Nine Months Ended September 30, 2023 2022 (in millions) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 1.3 $ 2.5 Financing cash flows used for finance leases 0.2 0.1
Restructuring, Impairment, and Other Activities Disclosure	Lease Exit and Disposal Costs During the nine months ended September 30, 2023, the Company recorded a non-recurring charge in connection with the early termination of the lease associated with the Company's former corporate headquarters in Reno, Nevada. This charge included a one-time lease termination payment of $7.6 million, a write-off related to remaining leasehold improvements and furniture and equipment of $2.6 million, and estimated miscellaneous expenses associated with exiting the property of $0.2 million. The Company also recognized a lease termination gain pertaining to the elimination of the lease liability net of the right-of-use asset of $1.0 million, which amount is included in Other expenses on the Company’s Consolidated Statements of Comprehensive Income (Loss). The decision to terminate this operating lease was undertaken as part of an ongoing review of the Company's current and future facility needs.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Taxes [Abstract]
Income Taxes	Income TaxesThe Company’s effective tax rate for the three and nine months ended September 30, 2023 was 19.5% and 19.7%, respectively, and the Company’s effective tax rate for the three months ended September 30, 2022 was 19.7%. The Company's effective tax rate for the nine months ended September 30, 2022 was not meaningful. The effective rates during each of the periods presented included income tax benefits and exclusions associated with tax-advantaged investment income, LPT adjustments, and deferred gain amortization.

Liability for Unpaid Losses and

Liability for Unpaid Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2023
Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Liability for Unpaid Losses and Loss Adjustment Expenses	Liability for Unpaid Losses and Loss Adjustment Expenses The following table represents a reconciliation of changes in the liability for unpaid losses and LAE. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Unpaid losses and LAE at beginning of period $ 1,927.2 $ 1,972.8 $ 1,960.7 $ 1,981.2 Less reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE 436.2 462.4 445.4 476.9 Net unpaid losses and LAE at beginning of period 1,491.0 1,510.4 1,515.3 1,504.3 Losses and LAE, net of reinsurance, incurred during the period related to: Current period 116.9 114.6 338.7 316.3 Prior periods (0.1) (0.3) (20.0) (10.3) Total net losses and LAE incurred during the period 116.8 114.3 318.7 306.0 Paid losses and LAE, net of reinsurance, related to: Current period 32.0 27.3 64.1 50.4 Prior periods 89.0 73.9 283.1 236.4 Total net paid losses and LAE during the period 121.0 101.2 347.2 286.8 Ending unpaid losses and LAE, net of reinsurance 1,486.8 1,523.5 1,486.8 1,523.5 Reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE 426.6 456.4 426.6 456.4 Unpaid losses and LAE at end of period $ 1,913.4 $ 1,979.9 $ 1,913.4 $ 1,979.9 Total net losses and LAE included in the above table exclude amortization of the deferred reinsurance gain—LPT Agreement, which totaled $1.9 million and $2.1 million for the three months ended September 30, 2023 and 2022, respectively, and $5.9 million and $6.3 million for the nine months ended September 30, 2023 and 2022, respectively (see Note 9). The change in incurred losses and LAE attributable to prior periods for the three months ended September 30, 2023 represented net favorable loss reserve development on the Company's assigned risk business. The change in incurred losses and LAE attributable to prior periods for the nine months ended September 30, 2023 represented net favorable loss reserve development recognized on the Company's voluntary business. The net loss reserve development recognized on voluntary business during the nine months ended September 30, 2023 resulted from favorable loss experience. The change in incurred losses and LAE attributable to prior periods for the three months ended September 30, 2022 represented net favorable loss reserve development on the Company's assigned risk business. The change in incurred losses and LAE attributable to prior periods for the nine months ended September 30, 2022 represented $9.6 million of net favorable development recognized on the Company's voluntary business, with the remaining balance relating to assigned risk business. The net loss reserve development recognized on voluntary business during the nine months ended September 30, 2022 resulted from favorable loss experience.

LPT Agreement

LPT Agreement	9 Months Ended
	Sep. 30, 2023
LPT Agreement [Abstract]
LPT Agreement	LPT Agreement The Company is party to the LPT Agreement under which $1.5 billion in liabilities for losses and LAE related to claims incurred by the Fund prior to July 1, 1995 were reinsured for consideration of $775.0 million. The LPT Agreement provides coverage up to $2.0 billion. The Company records its estimate of contingent profit commission in the accompanying Consolidated Balance Sheets as Contingent commission receivable–LPT Agreement and a corresponding liability is recorded in the accompanying Consolidated Balance Sheets in Deferred reinsurance gain–LPT Agreement. The Deferred Gain is being amortized using the recovery method. Amortization is determined by the proportion of actual reinsurance recoveries to total estimated recoveries over the life of the LPT Agreement, except for the contingent profit commission, which is amortized through June 30, 2024, the date through which the Company is entitled to receive a contingent profit commission under the LPT Agreement. The amortization is recorded in losses and LAE incurred in the accompanying Consolidated Statements of Comprehensive Income (Loss). Any adjustments to the Deferred Gain are recorded in losses and LAE incurred in the accompanying Consolidated Statements of Comprehensive Income (Loss). The Company amortized $1.9 million and $2.1 million of the Deferred Gain for the three months ended September 30, 2023 and 2022, respectively, and $5.9 million and $6.3 million for the nine months ended September 30, 2023 and 2022, respectively. The remaining Deferred Gain was $100.2 million and $106.1 million as of September 30, 2023 and December 31, 2022, respectively. The estimated remaining liabilities subject to the LPT Agreement were $294.4 million and $308.6 million as of September 30, 2023 and December 31, 2022, respectively. Losses and LAE paid with respect to the LPT Agreement totaled $873.0 million and $858.9 million from inception through September 30, 2023 and December 31, 2022, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2023
Accumulated Other Comprehensive Income [Abstract]
Accumulated Other Comprehensive Income, Net	Accumulated Other Comprehensive Loss Accumulated other comprehensive loss is comprised of unrealized gains and losses on investments classified as AFS, net of deferred taxes. The following table summarizes the components of accumulated other comprehensive loss: September 30, 2023 December 31, 2022 (in millions) Net unrealized losses on investments, before taxes $ (198.2) $ (175.8) Deferred tax benefit on net unrealized losses 41.6 36.9 Total accumulated other comprehensive loss $ (156.6) $ (138.9)

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2023
Stock-Based Compensation [Abstract]
Stock-Based compensation	Stock-Based Compensation The Company awarded restricted stock units (RSUs) and performance share units (PSUs) to certain employees and non-employee Directors of the Company as follows: Number Awarded Weighted Average Fair Value on Date of Grant Aggregate Fair Value on Date of Grant (in millions) March 2023 RSUs (1) 12,732 $ 44.27 0.6 RSUs (1) 64,520 41.14 2.7 PSUs (2) 81,800 41.14 3.4 May 2023 RSUs (1) 2,260 $ 37.83 $ 0.1 PSUs (2) 1,220 37.83 — RSUs (3) 18,664 35.32 0.7 August 2023 RSUs (1) 5,176 $ 38.45 $ 0.2 (1) These RSUs were awarded to certain employees of the Company and vest 25% on March 15, 2024, May 15, 2024 and August 15, 2024, as applicable, and each of the subsequent three anniversaries of those dates. (2) These PSUs were awarded to certain employees of the Company and have a performance period of three years. The PSU awards are subject to certain performance goals with payouts that range from 0% to 250% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level. (3) These RSUs were awarded to non-employee directors of the Company and vest in full on May 25, 2024. Employees who are awarded RSUs and PSUs are entitled to receive dividend equivalents for eligible awards, payable in cash, when and if, the underlying award vests and becomes payable. If the underlying award does not vest or is forfeited, dividend equivalents with respect to the underlying award fail to become payable and are forfeited. RSUs and PSUs are subject to accelerated vesting in certain circumstances, including but not limited to: death, disability, retirement, or in connection with a change of control of the Company. There were 23,500 stock options exercised during the nine months ended September 30, 2023 and there were 41,665 stock options exercised during the nine months ended September 30, 2022, and the year ended December 31, 2022. As of September 30, 2023, the Company no longer had any stock options outstanding. As of September 30, 2023, the Company had 278,526 RSUs, and 203,173 PSUs (based on the target achievement for the PSUs awarded) outstanding.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Common Share Basic earnings per share is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilutive impact of all common stock equivalents on earnings per share. Diluted earnings per share includes common shares assumed issued under the “treasury stock method,” which reflects the potential dilution that would occur if outstanding RSUs and PSUs vested and stock options were to be exercised. Employees who are awarded RSUs and PSUs are entitled to receive dividend equivalents for eligible awards, payable in cash, when and if, the underlying award vests and becomes payable. Therefore, these awards are not considered participating securities for the purposes of determining earnings per share. The following table presents the net income and the weighted average number of shares outstanding used in the earnings per common share calculations. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions, except share data) Net income $ 14.0 $ 19.1 $ 72.5 $ 1.3 Weighted average number of shares outstanding—basic 25,981,984 27,312,409 26,612,443 27,504,566 Effect of dilutive securities: PSUs 104,549 97,343 110,495 132,760 Stock options — 6,901 2,762 12,449 RSUs 31,747 19,775 41,356 31,891 Potential dilutive shares 136,296 124,019 154,613 177,100 Weighted average number of shares outstanding—diluted 26,118,280 27,436,428 26,767,056 27,681,666 Diluted earnings per share excludes outstanding potential dilutive shares in periods where the inclusion of such securities would be anti-dilutive under the treasury stock methodology. During the three and nine months ended September 30, 2023, 12,328 and 29,860 potential dilutive shares, respectively, were excluded from the Company's diluted earnings per share computations because they were determined to be anti-dilutive. During the three and nine months ended September 30, 2022, no potential dilutive shares were excluded from the Company's diluted earnings per share computations because none were determined to be anti-dilutive. No outstanding PSUs and RSUs are considered in the Company’s diluted earnings per share computations in any period that involves a net loss because their inclusion would be anti-dilutive.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	Segment Reporting The Company has determined that it has two reportable segments: Employers and Cerity. Each of these segments represents a separate and distinct underwriting platform through which the Company conducts insurance business. The nature and composition of each reportable segment and its Corporate and Other activities are as follows: The Employers segment represents the traditional business offered through the EMPLOYERS brand name (Employers) through its agents, including business originated from its strategic partnerships and alliances. The Cerity segment represents the business offered under the Cerity brand name, which includes the Company's direct-to-customer business. Corporate and Other activities consist of EHI expenses (which are not considered to be underwriting in nature), the financial impact of the LPT agreement (which is recorded as a reduction to Losses and loss adjustment expenses) and legacy business assumed and ceded by CIC. These expenses are not considered to be part of a reportable segment and are not otherwise allocated to a reportable segment. The Company has determined that it is not practicable to report identifiable assets by segment since certain assets are used interchangeably among the segments. The following table summarizes the Company's written premium and components of net income (loss) before income taxes by reportable segment. Employers Cerity Corporate and Other Total (in millions) Three Months Ended September 30, 2023 Gross premiums written $ 194.0 $ 2.2 $ — $ 196.2 Net premiums written 192.3 2.2 — 194.5 Net premiums earned 182.7 1.9 — 184.6 Net investment income 23.4 1.6 0.9 25.9 Net realized and unrealized losses on investments (5.9) (0.4) (0.8) (7.1) Other income 0.1 — — 0.1 Total revenues 200.3 3.1 0.1 203.5 Losses and loss adjustment expenses 115.5 1.3 (1.9) 114.9 Commission expense 26.6 0.1 — 26.7 Underwriting and general and administrative expenses 36.5 3.6 3.4 43.5 Interest and financing expenses 0.9 — 0.1 1.0 Total expenses 179.5 5.0 1.6 186.1 Net income (loss) before income taxes $ 20.8 $ (1.9) $ (1.5) $ 17.4 Three Months Ended September 30, 2022 Gross premiums written $ 187.1 $ 1.5 $ — $ 188.6 Net premiums written 185.3 1.5 — 186.8 Net premiums earned 177.9 0.8 — 178.7 Net investment income 21.4 1.2 1.1 23.7 Net realized and unrealized gains (losses) on investments 2.4 (0.3) (0.2) 1.9 Other income 0.1 — — 0.1 Total revenues 201.8 1.7 0.9 204.4 Losses and loss adjustment expenses 113.8 0.6 (2.1) 112.3 Commission expense 25.2 0.1 — 25.3 Underwriting and general and administrative expenses 35.7 3.4 2.8 41.9 Interest and financing expenses 1.0 — 0.1 1.1 Total expenses 175.7 4.1 0.8 180.6 Net income (loss) before income taxes $ 26.1 $ (2.4) $ 0.1 $ 23.8 Employers Cerity Corporate and Other Total (in millions) Nine Months Ended September 30, 2023 Gross premiums written $ 584.4 $ 5.1 $ — $ 589.5 Net premiums written 579.1 5.1 — 584.2 Net premiums earned 529.5 4.9 — 534.4 Net investment income 72.3 5.0 3.0 80.3 Net realized and unrealized gains (losses) on investments 11.1 (0.2) (0.2) 10.7 Other (loss) income (0.2) — — (0.2) Total revenues 612.7 9.7 2.8 625.2 Losses and loss adjustment expenses 315.5 3.2 (5.9) 312.8 Commission expense 73.6 0.2 — 73.8 Underwriting and general and administrative expenses 111.8 12.0 9.9 133.7 Interest and financing expenses 4.9 — 0.3 5.2 Other expenses 9.4 — — 9.4 Total expenses 515.2 15.4 4.3 534.9 Net income (loss) before income taxes $ 97.5 $ (5.7) $ (1.5) $ 90.3 Nine Months Ended September 30, 2022 Gross premiums written $ 536.8 $ 3.6 $ — $ 540.4 Net premiums written 531.7 3.6 — 535.3 Net premiums earned 492.1 2.0 — 494.1 Net investment income 57.7 2.7 2.4 62.8 Net realized and unrealized losses on investments (56.0) (1.6) (7.9) (65.5) Other income 0.3 — — 0.3 Total revenues 494.1 3.1 (5.5) 491.7 Losses and loss adjustment expenses 304.7 1.3 (6.3) 299.7 Commission expense 69.8 0.1 — 69.9 Underwriting and general and administrative expenses 101.8 9.9 8.9 120.6 Interest and financing expenses 1.3 — 0.3 1.6 Total expenses 477.6 11.3 2.9 491.8 Net income (loss) before income taxes $ 16.5 $ (8.2) $ (8.4) $ (0.1) Entity-Wide Disclosures The Company operates solely within the U.S. and does not have revenue from transactions with a single policyholder accounting for 10% or more of its revenues. In-force premiums represent the estimated annual premium on all policies that are active and in-force on such date. More specifically, in-force premiums include policy endorsements but exclude estimated final audit premiums. When adjusting for estimated final audit premium, our total in-force premiums were $722.1 million, $665.0 million, $649.1 million, and $613.7 million as of September 30, 2023, December 31, 2022, September 30, 2022, and December 31, 2021, respectively. The Company's management focuses on in-force premium because it represents premium that is available for renewal in the future. The following table shows our in-force premiums, in-force premiums including estimated final audit premium, and number of policies in-force for each of our largest states and all other states combined for the periods presented: September 30, 2023 December 31, 2022 September 30, 2022 December 31, 2021 State In-force Premiums Policies In-force Premiums Policies In-force Policies In-force Policies (dollars in millions) California $ 301.9 43,272 $ 279.7 42,876 $ 272.9 42,934 $ 258.4 40,704 Florida 55.4 10,052 49.4 9,417 46.8 9,034 41.1 7,989 New York 31.1 7,570 27.3 7,497 26.4 7,577 24.5 7,307 Other (43 states and D.C.) 287.6 65,226 266.1 61,566 260.8 60,602 247.4 55,350 Total in-force $ 676.0 126,120 $ 622.5 121,356 $ 606.9 120,147 $ 571.4 111,350 Estimated audit premium 46.1 — 42.5 — 42.2 — 42.3 — Total in-force, including $ 722.1 126,120 $ 665.0 121,356 $ 649.1 120,147 $ 613.7 111,350

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income	$ 14	$ 19.1	$ 72.5	$ 1.3

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Item 5. Other Information Rule 10b5-1 Trading Plans During the three months ended September 30, 2023, no director or officer of the Company adopted or terminated a "Rule 10b5-1 trading arrangement" or "non-Rule 10b5-1 trading arrangement," as each such term is defined in Item 408(a) of Regulation S-K.

Valuation of Financial Instru_2

Valuation of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value of Financial Instruments [Abstract]
Estimated fair value of financial instruments table	The carrying value and the estimated fair value of the Company’s financial instruments at fair value were as follows: September 30, 2023 December 31, 2022 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (in millions) Financial assets Total investments at fair value $ 2,237.0 $ 2,237.0 $ 2,502.4 $ 2,502.4 Cash and cash equivalents 108.8 108.8 89.2 89.2 Restricted cash and cash equivalents 0.2 0.2 0.2 0.2
Fair value, assets and liabilities measured on recurring basis table	The following table presents the Company’s investments at fair value and the corresponding fair value measurements. September 30, 2023 December 31, 2022 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (in millions) Fixed maturity securities: U.S. Treasuries $ — $ 94.1 $ — $ — $ 90.8 $ — U.S. Agencies — 2.1 — — 2.1 — States and municipalities — 228.2 — — 317.6 — Corporate securities — 896.0 21.9 — 851.9 16.2 Residential mortgage-backed securities — 343.3 — — 360.2 — Commercial mortgage-backed securities — 56.8 — — 55.1 — Asset-backed securities — 96.4 10.4 — 58.1 8.0 Collateralized loan obligations — 126.6 — — 260.9 — Foreign government securities — 9.3 — — 10.2 — Other securities — 112.1 — — 155.2 — Total fixed maturity securities $ — $ 1,964.9 $ 32.3 $ — $ 2,162.1 $ 24.2 Equity securities at fair value: Industrial and miscellaneous $ 166.6 $ — $ — $ 165.3 $ — $ — Other 26.4 — — 31.7 — — Total equity securities at fair value $ 193.0 $ — $ — $ 197.0 $ — $ — Short-term investments $ 33.3 $ 13.5 $ — $ 119.1 $ — $ — Total investments at fair value $ 226.3 $ 1,978.4 $ 32.3 $ 316.1 $ 2,162.1 $ 24.2
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block]	Financial Instruments Carried at Net Asset Value The Company has investments in private equity limited partnership interests that are included in Other invested assets on the Company’s Consolidated Balance Sheets. These investments do not have readily determinable fair values and are carried at net asset value (NAV) and therefore are excluded from the fair value hierarchy. The Company initially estimates the value of these investments using the transaction price. In subsequent periods, the Company measures these investments using NAV per share provided quarterly by the general partner, based on financial statements that are audited annually. These investments are generally not redeemable by the investees and cannot be sold without approval of the general partner. These investments have fund terms of 3 to 12 years, subject to two or three one Additionally, certain cash equivalents, principally money market securities, are measured using NAV, which approximates fair value. September 30, 2023 December 31, 2022 (in millions) Cash equivalents carried at NAV $ 99.7 $ 65.5 Other invested assets carried at NAV 90.9 59.7
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the nine months ended September 30, 2023. Level 3 Securities (in millions) Beginning balance, January 1, 2023 $ 24.2 Purchases 8.7 Unrealized losses included in comprehensive income or loss (0.6) Ending balance, September 30, 2023 $ 32.3

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2023
Investments [Abstract]
Debt Securities, Available-for-sale	The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s available-for-sale (AFS) investments were as follows: Amortized Allowance for Current Expected Credit Losses Gross Gross Estimated (in millions) At September 30, 2023 Fixed maturity securities U.S. Treasuries $ 98.9 $ — $ — $ (4.8) $ 94.1 U.S. Agencies 2.2 — — (0.1) 2.1 States and municipalities 240.8 — 0.1 (12.7) 228.2 Corporate securities 1,023.9 (2.6) 1.3 (104.7) 917.9 Residential mortgage-backed securities 401.3 — — (58.0) 343.3 Commercial mortgage-backed securities 64.5 — — (7.7) 56.8 Asset-backed securities 113.6 — 0.1 (6.9) 106.8 Collateralized loan obligations 127.8 — — (1.2) 126.6 Foreign government securities 12.7 — — (3.4) 9.3 Other securities (1) 112.9 (0.6) 0.7 (0.9) 112.1 Total fixed maturity securities $ 2,198.6 $ (3.2) $ 2.2 $ (200.4) $ 1,997.2 Short-term investments 46.8 — — — 46.8 Total AFS investments $ 2,245.4 $ (3.2) $ 2.2 $ (200.4) $ 2,044.0 At December 31, 2022 Fixed maturity securities U.S. Treasuries $ 95.1 $ — $ 0.1 $ (4.4) $ 90.8 U.S. Agencies 2.2 — — (0.1) 2.1 States and municipalities 326.7 — 0.8 (9.9) 317.6 Corporate securities 963.4 (2.8) 2.0 (94.5) 868.1 Residential mortgage-backed securities 403.5 — 0.3 (43.6) 360.2 Commercial mortgage-backed securities 61.5 — — (6.4) 55.1 Asset-backed securities 74.0 — 0.1 (8.0) 66.1 Collateralized loan obligations 268.1 — — (7.2) 260.9 Foreign government securities 13.0 — — (2.8) 10.2 Other securities (1) 159.2 (1.7) 0.6 (2.9) 155.2 Total fixed maturity securities $ 2,366.7 $ (4.5) $ 3.9 $ (179.8) $ 2,186.3 Short-term investments 119.1 — — — 119.1 Total AFS investments $ 2,485.8 $ (4.5) $ 3.9 $ (179.8) $ 2,305.4 (1) Other securities within fixed maturity securities consist of bank loans, which are classified as AFS and reported at fair value.
Equity securities table	The cost and estimated fair value of the Company’s equity securities recorded at fair value at September 30, 2023 and December 31, 2022 were as follows: Cost Estimated Fair Value (in millions) At September 30, 2023 Equity securities at fair value Industrial and miscellaneous $ 104.4 $ 166.6 Other 21.9 26.4 Total equity securities at fair value $ 126.3 $ 193.0 At December 31, 2022 Equity securities at fair value Industrial and miscellaneous $ 115.3 $ 165.3 Other 28.9 31.7 Total equity securities at fair value $ 144.2 $ 197.0
Other invested assets	The Company had Other invested assets totaling $90.9 million and $59.7 million (initial cost of $81.1 million and $54.4 million) at September 30, 2023 and December 31, 2022, respectively, consisting of private equity limited partnerships, which are carried at NAV based on information provided by the general partner. These investments are non-redeemable until conversion and are periodically evaluated by the Company for impairment based on the ultimate recovery of the investment. Changes in the value of these investments are recorded through Net realized and unrealized gains and losses on the Company’s Consolidated Statements of Comprehensive Income (Loss).
Investments classified by contractual maturity date table	The amortized cost and estimated fair value of the Company’s fixed maturity securities at September 30, 2023, by contractual maturity, are shown below. Expected maturities differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Cost Estimated Fair Value (in millions) Due in one year or less $ 87.3 $ 85.9 Due after one year through five years 716.0 677.7 Due after five years through ten years 601.0 527.0 Due after ten years 87.1 73.1 Mortgage and asset-backed securities 707.2 633.5 Total $ 2,198.6 $ 1,997.2
Unrealized loss on investments table	The following is a summary of AFS investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 months or greater in each case as of September 30, 2023 and December 31, 2022. September 30, 2023 December 31, 2022 Estimated Fair Value Gross Number of Issues Estimated Fair Value Gross Number of Issues (dollars in millions) Less than 12 months: Fixed maturity securities U.S. Treasuries $ 29.6 $ (0.6) 12 $ 76.8 $ (3.5) 13 U.S. Agencies — — — 2.1 (0.1) 1 States and municipalities 122.3 (4.0) 44 193.4 (9.0) 68 Corporate securities 133.1 (5.4) 42 763.3 (76.4) 335 Residential mortgage-backed securities 42.3 (1.3) 43 236.8 (17.9) 186 Commercial mortgage-backed securities — — — 52.5 (5.7) 22 Asset-backed securities 46.7 (0.5) 24 27.6 (2.6) 22 Collateralized loan obligations — — — 209.9 (5.5) 37 Other securities 18.7 (0.3) 88 81.6 (1.8) 224 Total fixed maturity securities 392.7 (12.1) 253 1,644.0 (122.5) 908 Total less than 12 months $ 392.7 $ (12.1) 253 $ 1,644.0 $ (122.5) 908 12 months or greater: Fixed maturity securities U.S. Treasuries $ 63.8 $ (4.2) 11 $ 11.2 $ (0.9) 4 US Agencies 2.1 (0.1) 1 — — — States and municipalities 95.7 (8.7) 40 5.4 (0.9) 3 Corporate securities 770.9 (99.3) 369 84.6 (18.1) 84 Residential mortgage-backed securities 295.1 (56.7) 225 106.6 (25.7) 65 Commercial mortgage-backed securities 51.8 (7.7) 24 2.6 (0.7) 3 Asset-backed securities 49.1 (6.4) 31 27.7 (5.4) 11 Collateralized loan obligations 121.6 (1.2) 28 36.9 (1.7) 11 Foreign government securities 9.3 (3.4) 2 10.2 (2.8) 3 Other securities 20.8 (0.6) 99 38.4 (1.1) 119 Total fixed maturity securities 1,480.2 (188.3) 830 323.6 (57.3) 303 Total 12 months or greater $ 1,480.2 $ (188.3) 830 $ 323.6 $ (57.3) 303
Unrealized gain (loss) on investments	Net realized gains and losses on investments and the change in unrealized gains and losses on the Company’s investments recorded at fair value are determined on a specific-identification basis and were as follows: Gross Realized Gains Gross Realized Losses Net Decrease (Increase) in CECL Allowance Change in Net Unrealized Gains (Losses) Changes in Fair Value Reflected in Earnings Changes in Fair Value Reflected in AOCI (1) , before tax (in millions) Three Months Ended September 30, 2023 Fixed maturity securities 0.3 $ (2.6) $ 1.1 $ (33.1) $ (1.2) $ (33.1) Equity securities — (1.5) — (5.8) (7.3) — Other invested assets — — — 1.4 1.4 — Total investments $ 0.3 $ (4.1) $ 1.1 $ (37.5) $ (7.1) $ (33.1) Nine Months Ended September 30, 2023 Fixed maturity securities $ 1.0 $ (5.2) $ 1.3 $ (22.4) $ (2.9) $ (22.4) Equity securities 0.1 (4.9) — 13.9 9.1 — Other invested assets — — — 4.5 4.5 — Total investments $ 1.1 $ (10.1) $ 1.3 $ (4.0) $ 10.7 $ (22.4) Three Months Ended September 30, 2022 Fixed maturity securities $ 0.1 $ (0.3) $ 5.2 $ (81.3) $ 5.0 $ (81.3) Equity securities 19.4 (5.1) — (16.6) (2.3) — Other invested assets — — — (0.8) (0.8) — Total investments $ 19.5 $ (5.4) $ 5.2 $ (98.7) $ 1.9 $ (81.3) Nine Months Ended September 30, 2022 Fixed maturity securities $ 2.5 $ (1.4) $ (4.5) $ (277.8) $ (3.4) $ (277.8) Equity securities 41.1 (14.0) — (90.4) (63.3) — Other invested assets — — — 1.2 1.2 — Total investments $ 43.6 $ (15.4) $ (4.5) $ (367.0) $ (65.5) $ (277.8)
Investment income table	Net investment income was as follows: Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Fixed maturity securities $ 22.6 $ 20.9 $ 69.7 $ 57.5 Equity securities 1.6 2.1 5.2 6.6 Other invested assets 1.1 0.9 2.9 1.8 Short-term investments 0.4 — 2.1 — Cash equivalents and restricted cash 1.4 0.7 3.2 0.8 Gross investment income 27.1 24.6 83.1 66.7 Investment expenses (1.2) (0.9) (2.8) (3.9) Net investment income $ 25.9 $ 23.7 $ 80.3 $ 62.8

Current Expected Credit Losses

Current Expected Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2023
Credit Loss [Abstract]
Premium Receivable, Allowance for Credit Loss [Table Text Block]	The table below shows the changes in CECL on premiums receivable. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on premiums receivable $ 15.2 $ 9.7 $ 12.8 $ 10.3 Net change in CECL provision 3.7 2.8 10.9 6.6 Write-offs charged against CECL (0.7) (0.1) (1.9) (1.9) Recoveries collected (2.0) (1.4) (5.6) (4.0) Ending balance of CECL on premiums receivable $ 16.2 $ 11.0 $ 16.2 $ 11.0
Reinsurance Recoverable, Allowance for Credit Loss [Table Text Block]	The table below shows the changes in CECL on reinsurance recoverables. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on reinsurance recoverables $ 0.9 $ 0.6 $ 0.9 $ 0.6 Net change in CECL provision — — — — Ending balance of CECL on reinsurance recoverables $ 0.9 $ 0.6 $ 0.9 $ 0.6
Debt Securities, Available-for-sale, Allowance for Credit Loss [Table Text Block]	The table below shows the changes in the allowance for CECL on available-for-sale securities. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Beginning balance of CECL on AFS securities $ 4.3 $ 10.0 $ 4.5 $ 0.2 Net change in CECL provision (0.2) (5.2) 0.2 4.7 Reductions in allowance from disposals (0.9) — (1.5) — Recoveries of amounts previously written off — (0.1) — (0.2) Ending balance of CECL on AFS securities $ 3.2 $ 4.7 $ 3.2 $ 4.7

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment [Table Text Block]	Property and equipment consists of the following: As of September 30, As of December 31, 2023 2022 (in millions) Furniture and equipment $ 1.8 $ 3.3 Leasehold improvements 0.6 5.0 Computers and software 44.9 47.6 Automobiles 0.7 0.8 Property and equipment, gross 48.0 56.7 Accumulated depreciation (41.0) (44.7) Property and equipment, net $ 7.0 $ 12.0
Lease, Cost [Table Text Block]	Components of lease expense were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Operating lease expense $ 0.2 $ 0.9 $ 1.3 $ 2.6 Finance lease expense — 0.1 0.1 0.1 Total lease expense $ 0.2 $ 1.0 $ 1.4 $ 2.7
Lessee, Operating and Finance Lease Liability Maturity [Table Text Block]	Maturities of lease liabilities were as follows: As of September 30, 2023 Operating Leases Finance Leases (in millions) 2023 $ 0.4 $ — 2024 1.5 0.1 2025 1.3 0.1 2026 0.9 — 2027 0.9 — Thereafter 0.2 — Total lease payments 5.2 0.2 Less: imputed interest (0.1) — Total $ 5.1 $ 0.2
Supplemental Balance Sheet Information related to Leases [Table Text Block]	Supplemental balance sheet information related to leases was as follows: As of September 30, As of December 31, 2023 2022 (in millions) Operating leases: Operating lease right-of-use asset $ 4.3 $ 11.5 Operating lease liability 5.1 13.6 Finance leases: Property and equipment, gross 0.7 0.8 Accumulated depreciation (0.4) (0.4) Property and equipment, net 0.3 0.4 Other liabilities $ 0.2 $ 0.4
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	Supplemental cash flow information related to leases was as follows: Nine Months Ended September 30, 2023 2022 (in millions) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows used for operating leases $ 1.3 $ 2.5 Financing cash flows used for finance leases 0.2 0.1

Liability for Unpaid Losses a_2

Liability for Unpaid Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2023
Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]
Changes in the liability for unpaid losses and LAE table	The following table represents a reconciliation of changes in the liability for unpaid losses and LAE. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions) Unpaid losses and LAE at beginning of period $ 1,927.2 $ 1,972.8 $ 1,960.7 $ 1,981.2 Less reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE 436.2 462.4 445.4 476.9 Net unpaid losses and LAE at beginning of period 1,491.0 1,510.4 1,515.3 1,504.3 Losses and LAE, net of reinsurance, incurred during the period related to: Current period 116.9 114.6 338.7 316.3 Prior periods (0.1) (0.3) (20.0) (10.3) Total net losses and LAE incurred during the period 116.8 114.3 318.7 306.0 Paid losses and LAE, net of reinsurance, related to: Current period 32.0 27.3 64.1 50.4 Prior periods 89.0 73.9 283.1 236.4 Total net paid losses and LAE during the period 121.0 101.2 347.2 286.8 Ending unpaid losses and LAE, net of reinsurance 1,486.8 1,523.5 1,486.8 1,523.5 Reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE 426.6 456.4 426.6 456.4 Unpaid losses and LAE at end of period $ 1,913.4 $ 1,979.9 $ 1,913.4 $ 1,979.9

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2023
Accumulated Other Comprehensive Income [Abstract]
Schedule of accumulated other comprehensive income (loss) table	The following table summarizes the components of accumulated other comprehensive loss: September 30, 2023 December 31, 2022 (in millions) Net unrealized losses on investments, before taxes $ (198.2) $ (175.8) Deferred tax benefit on net unrealized losses 41.6 36.9 Total accumulated other comprehensive loss $ (156.6) $ (138.9)

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Stock-Based Compensation [Abstract]
Share-based compensation arrangements by share-based payment award table	The Company awarded restricted stock units (RSUs) and performance share units (PSUs) to certain employees and non-employee Directors of the Company as follows: Number Awarded Weighted Average Fair Value on Date of Grant Aggregate Fair Value on Date of Grant (in millions) March 2023 RSUs (1) 12,732 $ 44.27 0.6 RSUs (1) 64,520 41.14 2.7 PSUs (2) 81,800 41.14 3.4 May 2023 RSUs (1) 2,260 $ 37.83 $ 0.1 PSUs (2) 1,220 37.83 — RSUs (3) 18,664 35.32 0.7 August 2023 RSUs (1) 5,176 $ 38.45 $ 0.2 (1) These RSUs were awarded to certain employees of the Company and vest 25% on March 15, 2024, May 15, 2024 and August 15, 2024, as applicable, and each of the subsequent three anniversaries of those dates. (2) These PSUs were awarded to certain employees of the Company and have a performance period of three years. The PSU awards are subject to certain performance goals with payouts that range from 0% to 250% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net income and weighted average common shares outstanding used in earnings per share calculations table	The following table presents the net income and the weighted average number of shares outstanding used in the earnings per common share calculations. Three Months Ended Nine Months Ended September 30, September 30, 2023 2022 2023 2022 (in millions, except share data) Net income $ 14.0 $ 19.1 $ 72.5 $ 1.3 Weighted average number of shares outstanding—basic 25,981,984 27,312,409 26,612,443 27,504,566 Effect of dilutive securities: PSUs 104,549 97,343 110,495 132,760 Stock options — 6,901 2,762 12,449 RSUs 31,747 19,775 41,356 31,891 Potential dilutive shares 136,296 124,019 154,613 177,100 Weighted average number of shares outstanding—diluted 26,118,280 27,436,428 26,767,056 27,681,666
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Diluted earnings per share excludes outstanding potential dilutive shares in periods where the inclusion of such securities would be anti-dilutive under the treasury stock methodology. During the three and nine months ended September 30, 2023, 12,328 and 29,860 potential dilutive shares, respectively, were excluded from the Company's diluted earnings per share computations because they were determined to be anti-dilutive. During the three and nine months ended September 30, 2022, no potential dilutive shares were excluded from the Company's diluted earnings per share computations because none were determined to be anti-dilutive. No outstanding PSUs and RSUs are considered in the Company’s diluted earnings per share computations in any period that involves a net loss because their inclusion would be anti-dilutive.

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2023
Net Income before income taxes by segment [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Employers Cerity Corporate and Other Total (in millions) Three Months Ended September 30, 2023 Gross premiums written $ 194.0 $ 2.2 $ — $ 196.2 Net premiums written 192.3 2.2 — 194.5 Net premiums earned 182.7 1.9 — 184.6 Net investment income 23.4 1.6 0.9 25.9 Net realized and unrealized losses on investments (5.9) (0.4) (0.8) (7.1) Other income 0.1 — — 0.1 Total revenues 200.3 3.1 0.1 203.5 Losses and loss adjustment expenses 115.5 1.3 (1.9) 114.9 Commission expense 26.6 0.1 — 26.7 Underwriting and general and administrative expenses 36.5 3.6 3.4 43.5 Interest and financing expenses 0.9 — 0.1 1.0 Total expenses 179.5 5.0 1.6 186.1 Net income (loss) before income taxes $ 20.8 $ (1.9) $ (1.5) $ 17.4 Three Months Ended September 30, 2022 Gross premiums written $ 187.1 $ 1.5 $ — $ 188.6 Net premiums written 185.3 1.5 — 186.8 Net premiums earned 177.9 0.8 — 178.7 Net investment income 21.4 1.2 1.1 23.7 Net realized and unrealized gains (losses) on investments 2.4 (0.3) (0.2) 1.9 Other income 0.1 — — 0.1 Total revenues 201.8 1.7 0.9 204.4 Losses and loss adjustment expenses 113.8 0.6 (2.1) 112.3 Commission expense 25.2 0.1 — 25.3 Underwriting and general and administrative expenses 35.7 3.4 2.8 41.9 Interest and financing expenses 1.0 — 0.1 1.1 Total expenses 175.7 4.1 0.8 180.6 Net income (loss) before income taxes $ 26.1 $ (2.4) $ 0.1 $ 23.8 Employers Cerity Corporate and Other Total (in millions) Nine Months Ended September 30, 2023 Gross premiums written $ 584.4 $ 5.1 $ — $ 589.5 Net premiums written 579.1 5.1 — 584.2 Net premiums earned 529.5 4.9 — 534.4 Net investment income 72.3 5.0 3.0 80.3 Net realized and unrealized gains (losses) on investments 11.1 (0.2) (0.2) 10.7 Other (loss) income (0.2) — — (0.2) Total revenues 612.7 9.7 2.8 625.2 Losses and loss adjustment expenses 315.5 3.2 (5.9) 312.8 Commission expense 73.6 0.2 — 73.8 Underwriting and general and administrative expenses 111.8 12.0 9.9 133.7 Interest and financing expenses 4.9 — 0.3 5.2 Other expenses 9.4 — — 9.4 Total expenses 515.2 15.4 4.3 534.9 Net income (loss) before income taxes $ 97.5 $ (5.7) $ (1.5) $ 90.3 Nine Months Ended September 30, 2022 Gross premiums written $ 536.8 $ 3.6 $ — $ 540.4 Net premiums written 531.7 3.6 — 535.3 Net premiums earned 492.1 2.0 — 494.1 Net investment income 57.7 2.7 2.4 62.8 Net realized and unrealized losses on investments (56.0) (1.6) (7.9) (65.5) Other income 0.3 — — 0.3 Total revenues 494.1 3.1 (5.5) 491.7 Losses and loss adjustment expenses 304.7 1.3 (6.3) 299.7 Commission expense 69.8 0.1 — 69.9 Underwriting and general and administrative expenses 101.8 9.9 8.9 120.6 Interest and financing expenses 1.3 — 0.3 1.6 Total expenses 477.6 11.3 2.9 491.8 Net income (loss) before income taxes $ 16.5 $ (8.2) $ (8.4) $ (0.1)
Revenue from External Customers by Geographic Areas [Table Text Block]	September 30, 2023 December 31, 2022 September 30, 2022 December 31, 2021 State In-force Premiums Policies In-force Premiums Policies In-force Policies In-force Policies (dollars in millions) California $ 301.9 43,272 $ 279.7 42,876 $ 272.9 42,934 $ 258.4 40,704 Florida 55.4 10,052 49.4 9,417 46.8 9,034 41.1 7,989 New York 31.1 7,570 27.3 7,497 26.4 7,577 24.5 7,307 Other (43 states and D.C.) 287.6 65,226 266.1 61,566 260.8 60,602 247.4 55,350 Total in-force $ 676.0 126,120 $ 622.5 121,356 $ 606.9 120,147 $ 571.4 111,350 Estimated audit premium 46.1 — 42.5 — 42.2 — 42.3 — Total in-force, including $ 722.1 126,120 $ 665.0 121,356 $ 649.1 120,147 $ 613.7 111,350

Basis of Presentation (Details)

Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Reportable Segments	2
Reinsurance Quota Share, Percentage	100%

Fair Value of Financial Instrum

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments at fair value	$ 2,237	$ 2,502.4
Total Investments at fair value, estimated fair value	2,237	2,502.4
Cash and cash equivalents	108.8	89.2
Cash and cash equivalents, estimated fair value	108.8	89.2
Restricted Cash and Cash Equivalents	0.2	0.2
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted Cash and Cash Equivalents	$ 0.2	$ 0.2

Fair Value of Financial Instr_2

Fair Value of Financial Instruments, Fair Value Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	$ 1,997.2	$ 2,186.3
Equity Securities, FV-NI	193	197
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	46.8	119.1
Investments	2,333.9	2,568.8
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	193	197
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	33.3	119.1
Investments	226.3	316.1
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0	0
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	13.5	0
Investments	1,978.4	2,162.1
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0	0
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	0	0
Investments	32.3	24.2
Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	1,964.9	2,162.1
Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	32.3	24.2
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	94.1	90.8
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	94.1	90.8
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	2.1	2.1
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	2.1	2.1
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	228.2	317.6
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	228.2	317.6
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	917.9	868.1
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	896	851.9
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	21.9	16.2
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	343.3	360.2
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	343.3	360.2
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	56.8	55.1
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	56.8	55.1
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	106.8	66.1
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	96.4	58.1
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	10.4	8
Foreign Government Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	9.3	10.2
Foreign Government Debt | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Foreign Government Debt | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	9.3	10.2
Foreign Government Debt | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	126.6	260.9
Collateralized Loan Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Collateralized Loan Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	126.6	260.9
Collateralized Loan Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Other Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	112.1	155.2
Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	112.1	155.2
Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, fair value	0	0
Industrial and Miscellaneous [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	166.6	165.3
Industrial and Miscellaneous [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	166.6	165.3
Industrial and Miscellaneous [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0	0
Industrial and Miscellaneous [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0	0
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	26.4	31.7
Other [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	26.4	31.7
Other [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	0	0
Other [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	$ 0	$ 0

Valuation of Financial Instru_3

Valuation of Financial Instruments Investments at NAV (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Investments at NAV [Abstract]
Fair value investments entities that calculate net asset value per share liquidating investment original expected lives increments	1 year
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 28.6
Cash Equivalents Measured at Net Asset Value	99.7	$ 65.5
Other invested assets at NAV	$ 90.9	$ 59.7
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value investments entities that calculate net asset value per share liquidating investment original expected lives increments	1 year
Maximum [Member]
Investments at NAV [Abstract]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period	12 years
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period	12 years
Minimum [Member]
Investments at NAV [Abstract]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period	3 years
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period	3 years

Fair Value Measures nd Disclosu

Fair Value Measures nd Disclosures on recurring basis, unobservable inputs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	$ 8.7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	(0.6)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 32.3	$ 24.2

Investments Available for Sale

Investments Available for Sale Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	$ 2,198.6		$ 2,366.7
Debt securities, available-for-sale, gross unrealized gain	2.2		3.9
Debt securities, available-for-sale, gross unrealized loss	(200.4)		(179.8)
Fixed maturity securities, fair value	1,997.2		2,186.3
Total AFS, amortized cost	2,245.4		2,485.8
Total AFS, gross unrealized gain	2.2		3.9
Total AFS, gross unrealized loss	200.4		179.8
Short-term investments at fair value (amortized cost $46.8 at September 30, 2023 and $119.1 at December 31, 2022)	46.8		119.1
Total AFS investments	2,044		2,305.4
Debt Securities, Available-for-sale, Allowance for Credit Loss	(3.2)	$ (4.3)	(4.5)	$ (4.7)	$ (10)	$ (0.2)
Other invested assets (cost $81.1 at September 30, 2023 and $54.4 at December 31, 2022)	90.9		59.7
Other invested assets at NAV	90.9		59.7
Investment Owned, at Cost	81.1		54.4
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	98.9		95.1
Debt securities, available-for-sale, gross unrealized gain	0		0.1
Debt securities, available-for-sale, gross unrealized loss	(4.8)		(4.4)
Fixed maturity securities, fair value	94.1		90.8
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	2.2		2.2
Debt securities, available-for-sale, gross unrealized gain	0		0
Debt securities, available-for-sale, gross unrealized loss	(0.1)		(0.1)
Fixed maturity securities, fair value	2.1		2.1
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	240.8		326.7
Debt securities, available-for-sale, gross unrealized gain	0.1		0.8
Debt securities, available-for-sale, gross unrealized loss	(12.7)		(9.9)
Fixed maturity securities, fair value	228.2		317.6
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	1,023.9		963.4
Debt securities, available-for-sale, gross unrealized gain	1.3		2
Debt securities, available-for-sale, gross unrealized loss	(104.7)		(94.5)
Fixed maturity securities, fair value	917.9		868.1
Debt Securities, Available-for-sale, Allowance for Credit Loss	(2.6)		(2.8)
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	401.3		403.5
Debt securities, available-for-sale, gross unrealized gain	0		0.3
Debt securities, available-for-sale, gross unrealized loss	(58)		(43.6)
Fixed maturity securities, fair value	343.3		360.2
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	64.5		61.5
Debt securities, available-for-sale, gross unrealized gain	0		0
Debt securities, available-for-sale, gross unrealized loss	(7.7)		(6.4)
Fixed maturity securities, fair value	56.8		55.1
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	113.6		74
Debt securities, available-for-sale, gross unrealized gain	0.1		0.1
Debt securities, available-for-sale, gross unrealized loss	(6.9)		(8)
Fixed maturity securities, fair value	106.8		66.1
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Foreign Government Debt
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	12.7		13
Debt securities, available-for-sale, gross unrealized gain	0		0
Debt securities, available-for-sale, gross unrealized loss	(3.4)		(2.8)
Fixed maturity securities, fair value	9.3		10.2
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	127.8		268.1
Debt securities, available-for-sale, gross unrealized gain	0		0
Debt securities, available-for-sale, gross unrealized loss	(1.2)		(7.2)
Fixed maturity securities, fair value	126.6		260.9
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Other Debt Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost	112.9		159.2
Debt securities, available-for-sale, gross unrealized gain	0.7		0.6
Debt securities, available-for-sale, gross unrealized loss	(0.9)		(2.9)
Fixed maturity securities, fair value	112.1		155.2
Debt Securities, Available-for-sale, Allowance for Credit Loss	(0.6)		(1.7)
Short-term Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Total AFS, amortized cost	46.8		119.1
Total AFS, gross unrealized gain	0		0
Total AFS, gross unrealized loss	0		0
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0		$ 0

Investments Equity Securities (

Investments Equity Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Schedule of Equity Securities and Other [Line Items]
Equity Securities, FV-NI, Cost	$ 126.3	$ 144.2
Equity Securities, FV-NI	193	197
Industrial and Miscellaneous [Member]
Schedule of Equity Securities and Other [Line Items]
Equity Securities, FV-NI, Cost	104.4	115.3
Equity Securities, FV-NI	166.6	165.3
Other [Member]
Schedule of Equity Securities and Other [Line Items]
Equity Securities, FV-NI, Cost	21.9	28.9
Equity Securities, FV-NI	$ 26.4	$ 31.7

Investments Other Invested Asse

Investments Other Invested Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Other Invest Assets [Abstract]
Other invested assets at NAV	$ 90.9	$ 59.7
Investment Owned, at Cost	81.1	54.4
Total other invested assets	$ 90.9	$ 59.7

Investments, Amortized Cost and

Investments, Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less, amortized cost	$ 87.3
Due after one year through five years, amortized cost	716
Due after five years through ten years, amortized cost	601
Due after ten years, amortized cost	87.1
Mortgage and asset-backed securities, amortized cost	707.2
Debt securities, available-for-sale, amortized cost	2,198.6	$ 2,366.7
Estimated Fair Value
Due in one year or less, fair value	85.9
Due after one year through five years, fair value	677.7
Due after five years through ten years, fair value	527
Due after ten years, fair value	73.1
Mortgage and asset-backed securities, fair value	633.5
Total, fair value	$ 1,997.2	$ 2,186.3

Investments, Continuous Loss Po

Investments, Continuous Loss Position (Details) $ in Millions	Sep. 30, 2023 USD ($) shares shares	Dec. 31, 2022 USD ($) shares
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 392.7	$ 1,644
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,480.2	323.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(12.1)	(122.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (188.3)	$ (57.3)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	253	908
Debt Securities, number of issues in loss position, 12 months or greater	830	303
Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 392.7	$ 1,644
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,480.2	323.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(12.1)	(122.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (188.3)	$ (57.3)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	253	908
Debt Securities, number of issues in loss position, 12 months or greater | shares	830	303
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 29.6	$ 76.8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	63.8	11.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(0.6)	(3.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (4.2)	$ (0.9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	12	13
Debt Securities, number of issues in loss position, 12 months or greater	11	4
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 0	$ 2.1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2.1	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(0.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (0.1)	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	0	1
Debt Securities, number of issues in loss position, 12 months or greater	1	0
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 122.3	$ 193.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	95.7	5.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(4)	(9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (8.7)	$ (0.9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	44	68
Debt Securities, number of issues in loss position, 12 months or greater	40	3
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 133.1	$ 763.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	770.9	84.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(5.4)	(76.4)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (99.3)	$ (18.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	42	335
Debt Securities, number of issues in loss position, 12 months or greater	369	84
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 42.3	$ 236.8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	295.1	106.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1.3)	(17.9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (56.7)	$ (25.7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	43	186
Debt Securities, number of issues in loss position, 12 months or greater	225	65
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 0	$ 52.5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	51.8	2.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(5.7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (7.7)	$ (0.7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	0	22
Debt Securities, number of issues in loss position, 12 months or greater	24	3
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 46.7	$ 27.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	49.1	27.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(0.5)	(2.6)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (6.4)	$ (5.4)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	24	22
Debt Securities, number of issues in loss position, 12 months or greater	31	11
Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 0	$ 209.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	121.6	36.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(5.5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (1.2)	$ (1.7)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	0	37
Debt Securities, number of issues in loss position, 12 months or greater | shares	28	11
Foreign Government Debt
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 9.3	$ 10.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (3.4)	$ (2.8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, 12 months or greater | shares	2	3
Other Debt Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 18.7	$ 81.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	20.8	38.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(0.3)	(1.8)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (0.6)	$ (1.1)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Debt Securities, number of issues in loss position, less than 12 months | shares	88	224
Debt Securities, number of issues in loss position, 12 months or greater | shares	99	119

Investments Investments, Net Re

Investments Investments, Net Realized Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity securities:
Equity Securities, FV-NI, Realized Gain	$ 0	$ 19.4	$ 0.1	$ 41.1
Equity Securities, FV-NI, Realized Loss	1.5	5.1	4.9	14
AFS, change in unrealized gains (losses)
AFS, change unrealized gains (losses) on fixed maturity and equity securities reflected in AOCI	(33.1)	(81.3)	(22.4)	(277.8)
AFS, net realized gains (losses)
Net realized and unrealized (losses) gains on investments	(7.1)	1.9	10.7	(65.5)
Total gross realized gains	0.3	19.5	1.1	43.6
Investments, Gross Realized Losses	(4.1)	(5.4)	(10.1)	(15.4)
Total change in net unrealized gains (losses)	(37.5)	(98.7)	(4)	(367)
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Equity Securities, FV-NI, Unrealized Gain (Loss)	(5.8)	(16.6)	13.9	(90.4)
Proceeds from sale of fixed maturity securities	204	30.6	329.5	230.7
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	(1.1)	(5.2)	(1.3)	4.5
Debt Securities [Member]
AFS, change in unrealized gains (losses)
AFS, change unrealized gains (losses) on fixed maturity and equity securities reflected in AOCI	(33.1)	(81.3)	(22.4)	(277.8)
AFS, net realized gains (losses)
Net realized and unrealized (losses) gains on investments	(1.2)	5	(2.9)	(3.4)
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	(1.1)	(5.2)	(1.3)	4.5
Debt Securities, Available-for-sale, Realized Loss	2.6	0.3	5.2	1.4
Debt Securities, Available-for-sale, Realized Gain	0.3	0.1	1	2.5
Equity Securities [Member]
AFS, change in unrealized gains (losses)
AFS, change unrealized gains (losses) on fixed maturity and equity securities reflected in AOCI	0	0	0	0
AFS, net realized gains (losses)
Net realized and unrealized (losses) gains on investments	(7.3)	(2.3)	9.1	(63.3)
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	0	0	0	0
Other Investments [Member]
AFS, change in unrealized gains (losses)
AFS, change unrealized gains (losses) on fixed maturity and equity securities reflected in AOCI	0	0	0	0
AFS, net realized gains (losses)
Net realized and unrealized (losses) gains on investments	1.4	(0.8)	4.5	1.2
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	0	0	0	0
Gain on Sale of Investments	0	0	0	0
Loss on Sale of Investments	0	0	0	0
Unrealized Gain (Loss) on Investments	$ 1.4	$ (0.8)	$ 4.5	$ 1.2

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 27.1	$ 24.6	$ 83.1	$ 66.7
Investment expenses	1.2	0.9	2.8	3.9
Net investment income	25.9	23.7	80.3	62.8
Debt Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	22.6	20.9	69.7	57.5
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	1.6	2.1	5.2	6.6
Other Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	1.1	0.9	2.9	1.8
Short-term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	0.4	0	2.1	0
Cash and Cash Equivalents [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 1.4	$ 0.7	$ 3.2	$ 0.8

Investments Investments, Held i

Investments Investments, Held in Trust or on Deposit (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Other invested assets (cost $81.1 at September 30, 2023 and $54.4 at December 31, 2022)	$ 90.9	$ 59.7
Deposit Assets [Abstract]
Investments	2,333.9	2,568.8
Assets Held-in-trust [Abstract]
Funds Held under Reinsurance Agreements, Asset	2.7	2.7
Federal Home Loan Bank [Member]
Deposit Assets [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity	70	70
Required by various state laws and regulations to hold securities or letters of credit in depository account [Member]
Deposit Assets [Abstract]
Investments	$ 714.1	$ 745.9

Current Expected Credit Losse_2

Current Expected Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Current Expected Credit Losses [Abstract]
Premium Receivable, Allowance for Credit Loss	$ 16.2	$ 11	$ 16.2	$ 11	$ 15.2	$ 12.8	$ 9.7	$ 10.3
Premium Receivable, Allowance for Credit Loss, Period Increase (Decrease)	3.7	2.8	10.9	6.6
Premium Receivable, Allowance for Credit Loss, Writeoff	(0.7)	(0.1)	(1.9)	(1.9)
Premium Receivable, Allowance for Credit Loss, Recovery	(2)	(1.4)	(5.6)	(4)
Reinsurance recoverables on unpaid losses, allowance	0.9	0.6	0.9	0.6	0.9	0.9	0.6	0.6
Reinsurance Recoverable, Allowance for Credit Loss, Period Increase (Decrease)	0	0	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss	3.2	4.7	3.2	4.7	$ 4.3	4.5	$ 10	$ 0.2
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(0.9)	0	(1.5)	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Recovery	0	(0.1)	0	(0.2)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff	(0.2)	$ (5.2)	0.2	$ 4.7
Accrued investment income	$ 18.5		$ 18.5			$ 19

Property and Equipment Property

Property and Equipment Property and Equipment (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Property and Equipment [Line Items]
Property and equipment, gross	$ 56.7	$ 48	$ 48		$ 56.7
Accumulated depreciation, depletion and amortization, property and equipment	(44.7)	(41)	(41)		(44.7)
Property and equipment, net	12	7	7		12
Utilities operating expense, depreciation and amortization	5.3	1	3.7
Payments to develop software	1.2	0.5	1.2
Cloud computing arrangements	42.9	33.2	33.2		42.9
Amortization of cloud computing arrangements		4.2	12.6	$ 12.1	16.4
Furniture and equipment
Property and Equipment [Line Items]
Property and equipment, gross	3.3	1.8	1.8		3.3
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	5	0.6	0.6		5
Computer and software
Property and Equipment [Line Items]
Property and equipment, gross	47.6	44.9	44.9		47.6
Automobiles
Property and Equipment [Line Items]
Property and equipment, gross	$ 0.8	$ 0.7	$ 0.7		$ 0.8

Property and Equipment Leases (

Property and Equipment Leases (Details)	Sep. 30, 2023
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, remaining lease term	1 year
Lessee, Finance Lease, Term of Contract	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, remaining lease term	5 years
Lessee, operating lease, renewal term	5 years

Property and Equipment Leases,

Property and Equipment Leases, Components of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Components of Lease Expense [Abstract]
Operating lease expense	$ 0.2	$ 0.9	$ 1.3	$ 2.6
Finance lease expense	0	0.1	0.1	0.1
Total lease expense	$ 0.2	$ 1	$ 1.4	$ 2.7

Property and Equipment Leases_2

Property and Equipment Leases, Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Lessee, operating lease liabilities due
Operating lease liabilities due next twelve months	$ 0.4
Operating lease liabilities due year two	1.5
Operating lease liabilities due year three	1.3
Operating lease liabilities due year four	0.9
Operating lease liabilities due year five	0.9
Operating lease liabilities due after year five	0.2
Operating lease liabilities due	5.2
Less: inputed interest, Operating lease liability	(0.1)
Operating lease liability	$ 5.1	$ 13.6
Operating lease, weighted average remaining lease term	3 years 10 months 24 days
Operating lease, weighted average discount rate, percent	0.60%
Lessee, finance lease liabilities due
Finance lease liabilities due next twelve months	$ 0
Finance lease liabilities due year two	0.1
Finance lease liabilities due year three	0.1
Finance lease liabilities due year four	0
Finance lease liabilities due year five	0
Finance lease liabilities due after year five	0
Finance lease liabilities due	0.2
Less: inputed interest, finance lease	0
Finance lease, liability	$ 0.2	$ 0.4
Finance lease, weighted average remaining lease term	2 years 1 month 6 days
Finance lease, weighted average discount rate, percent	7.40%

Property and Equipment Leases_3

Property and Equipment Leases, Supplement Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 4.3	$ 11.5
Operating lease liability	5.1	13.6
Property and equipment, gross	48	56.7
Accumulated depreciation, depletion and amortization, property and equipment	(41)	(44.7)
Property and equipment, net	7	12
Other liabilities	58.3	57.1
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	0.7	0.8
Finance Lease, Right-of-Use Asset, Accumulated Amortization	0.4	0.4
Finance Lease, Right-of-Use Asset, after Accumulated Amortization	0.3	0.4
Finance lease, liability	$ 0.2	$ 0.4

Property and Equipment Leases_4

Property and Equipment Leases, Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Leases, Supplement Balance Sheet Information [Abstract]
Operating cash flows from operating leases	$ 1.3	$ 2.5
Financing cash flows from finance leases	$ 0.2	$ 0.1

Exit and Disposal Cost (Details

Exit and Disposal Cost (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Business Exit Costs	$ 7.6
Asset Impairment Charges	2.6	$ 0
Other General Expense	0.2
Gain (Loss) on Termination of Lease	$ 1	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Income tax expense (benefit)	$ 3.4	$ 4.7	$ 17.8	$ (1.4)
Effective tax rate	19.50%	19.70%	19.70%

Liability for Unpaid Losses a_3

Liability for Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid losses and LAE at beginning of period	$ 1,927.2	$ 1,972.8	$ 1,960.7	$ 1,981.2
Less reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE	436.2	462.4	445.4	476.9
Net unpaid losses and LAE at beginning of period	1,491	1,510.4	1,515.3	1,504.3
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	116.9	114.6	338.7	316.3
Prior periods	(0.1)	(0.3)	(20)	(10.3)
Total net losses and LAE incurred during the period	116.8	114.3	318.7	306
Deduct payments for losses and LAE, net of reinsurance, related to:
Current period	32	27.3	64.1	50.4
Prior periods	89	73.9	283.1	236.4
Total net paid losses and LAE during the period	121	101.2	347.2	286.8
Ending unpaid losses and LAE, net of reinsurance	1,486.8	1,523.5	1,486.8	1,523.5
Reinsurance recoverable, excluding CECL allowance, on unpaid losses and LAE	426.6	456.4	426.6	456.4
Unpaid losses and LAE at end of period	1,913.4	1,979.9	1,913.4	1,979.9
Impact of the LPT Agreement	$ 1.9	$ 2.1	$ 5.9	$ 6.3

LPT Agreement (Details)

LPT Agreement (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Reinsurance Agreement [Line Items]
Liabilities for the incurred but unpaid losses and LAE related to claims prior to July 1, 1995	$ 1,500		$ 1,500
Ceded premiums written			775
Amortization of deferred gain	1.9	$ 2.1	5.9	$ 6.3
Net income	14	19.1	72.5	1.3
Deferred reinsurance gain—LPT Agreement	100.2		100.2		$ 106.1
Estimated remaining liabilities - LPT Agreement	294.4		294.4		308.6
Paid losses and LAE claims related to LPT	873		873		$ 858.9
Impact of the LPT Agreement	1.9	$ 2.1	5.9	$ 6.3
Indemnification Agreement [Member]
Reinsurance Agreement [Line Items]
Coverage provided under LPT Agreement	$ 2,000		$ 2,000

Notes Payable Letters of Credit

Notes Payable Letters of Credit (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Letters of Credit Facilities [Line Items]
Letters of credit, unused capacity, commitment fee percentage			15%
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 40,400		$ 40,400		$ 182,500
Line of Credit Facility, Current Borrowing Capacity	75,000		$ 75,000
Line of Credit Facility, Commitment Fee Percentage			0.30%
Repayments on line of credit advances			$ 0	$ 10,000
Interest and financing expenses	1,000	$ 1,100	5,200	1,600
Line of Credit Facility, Commitment Fee Amount			25
Debt Issuance Costs, Gross	700		$ 700
Debt Instrument, Covenant Description			a minimum consolidated net worth of no less than $900.0 million
Line of Credit Facility, Covenant Terms			a debt to total capitalization ratio of no more than 35%, in each case as determined in accordance with the Amended Credit Agreement
Proceeds from FHLBank Advance, Investing Activities					182,500
Repayments of FHLBank Advance, Investing Activities			$ 142,100	0
Line of Credit Facility, Fair Value of Amount Outstanding	0		0
Proceeds from Lines of Credit			0	10,000
Line of Credit Facility, Periodic Payment, Interest	100	100	300	300
Interest Expense, Loans from Other Federal Home Loan Banks	$ 900	$ 1,000	$ 4,800	$ 1,200
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	5.06%		5.06%
Maximum [Member]
Letters of Credit Facilities [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 125,000		$ 125,000
Line of Credit Facility, Interest Rate at Period End	1.25%		1.25%
Debt Instrument, Interest Rate, Stated Percentage	2.25%		2.25%
Line of Credit Facility, Commitment Fee Percentage			0.50%
Line of Credit Facility, Commitment Fee Amount			$ 225
Minimum [Member]
Letters of Credit Facilities [Line Items]
Line of Credit Facility, Interest Rate at Period End	0.25%		0.25%
Debt Instrument, Interest Rate, Stated Percentage	1.25%		1.25%
Line of Credit Facility, Commitment Fee Percentage			0.20%
Federal Home Loan Bank [Member]
Letters of Credit Facilities [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 70,000		$ 70,000		70,000
Letters of credit collateral amount	$ 275,800		$ 275,800		$ 321,200

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income [Abstract]
Net unrealized losses on investments, before taxes	$ (198.2)	$ (175.8)
Deferred tax benefit on net unrealized losses	41.6	36.9
Total accumulated other comprehensive loss	$ (156.6)	$ (138.9)

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions							9 Months Ended		12 Months Ended
		Aug. 15, 2023	May 25, 2023	May 15, 2023	Mar. 15, 2023	Mar. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-options exercised							23,500	41,665	41,665
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, shares issued	[1]		18,664
Fair value of awards awarded on grant date	[1]		$ 0.7
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	[1]		$ 35.32
Restricted Stock Units (RSUs) [Member] | Management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, shares issued	[2]	5,176				12,732
Fair value of awards awarded on grant date	[2]	$ 0.2				$ 0.6
Number of outstanding options or share units							278,526
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	[2]	$ 38.45				$ 44.27
Restricted Stock Units (RSUs) [Member] | Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, shares issued	[2]			2,260	64,520
Fair value of awards awarded on grant date	[2]			$ 0.1	$ 2.7
Vesting rights for RSUs awarded							vest 25% on March 15, 2024, May 15, 2024 and August 15, 2024, as applicable, and each of the subsequent three anniversaries of those dates
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	[2]			$ 37.83	$ 41.14
Performance Shares [Member] | Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, shares issued	[3]			1,220	81,800
Fair value of awards awarded on grant date	[3]			$ 0	$ 3.4
Performance share awards performance period							three years
Performance share awards, minimum payout							0%
Performance share awards, maximum payout							250%
Number of outstanding options or share units							203,173
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	[3]			$ 37.83	$ 41.14
[1]These RSUs were awarded to non-employee directors of the Company and vest in full on May 25, 2024.[2]These RSUs were awarded to certain employees of the Company and vest 25% on March 15, 2024, May 15, 2024 and August 15, 2024, as applicable, and each of the subsequent three anniversaries of those dates.[3]These PSUs were awarded to certain employees of the Company and have a performance period of three years. The PSU awards are subject to certain performance goals with payouts that range from 0% to 250% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income available to stockholders - basic and diluted	$ 14	$ 19.1	$ 72.5	$ 1.3
Weighted average number of shares outstanding - basic	25,981,984	27,312,409	26,612,443	27,504,566
Effect of dilutive securities:
Dilutive securities	136,296	124,019	154,613	177,100
Weighted average number of shares outstanding - diluted	26,118,280	27,436,428	26,767,056	27,681,666
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	12,328	0	29,860	0
Performance Shares [Member]
Effect of dilutive securities:
Dilutive securities	104,549	97,343	110,495	132,760
Stock Option [Member]
Effect of dilutive securities:
Dilutive securities	0	6,901	2,762	12,449
Restricted Stock Units (RSUs) [Member]
Effect of dilutive securities:
Dilutive securities	31,747	19,775	41,356	31,891

Segment Reporting Segment Net I

Segment Reporting Segment Net Income Before Taxes (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments			2
Premiums Written, Gross	$ 196.2	$ 188.6	$ 589.5	$ 540.4
Premiums Written, Net	194.5	186.8	584.2	535.3
Net premiums earned	184.6	178.7	534.4	494.1
Net investment income	25.9	23.7	80.3	62.8
Net realized and unrealized (losses) gains on investments	(7.1)	1.9	10.7	(65.5)
Other income (loss)	0.1	0.1	(0.2)	0.3
Revenues	(203.5)	(204.4)	(625.2)	(491.7)
Losses and loss adjustment expenses	114.9	112.3	312.8	299.7
Commission expense	26.7	25.3	73.8	69.9
Underwriting and general and administrative expenses	43.5	41.9	133.7	120.6
Interest and financing expenses	1	1.1	5.2	1.6
Other Expenses	0	0	9.4	0
Operating Expenses	186.1	180.6	534.9	491.8
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	17.4	23.8	90.3	(0.1)
Employers Segment [Member]
Segment Reporting Information [Line Items]
Premiums Written, Gross	194	187.1	584.4	536.8
Premiums Written, Net	192.3	185.3	579.1	531.7
Net premiums earned	182.7	177.9	529.5	492.1
Net investment income	23.4	21.4	72.3	57.7
Net realized and unrealized (losses) gains on investments	(5.9)	2.4	11.1	(56)
Other income (loss)	0.1	0.1	(0.2)	0.3
Revenues	(200.3)	(201.8)	(612.7)	(494.1)
Losses and loss adjustment expenses	115.5	113.8	315.5	304.7
Commission expense	26.6	25.2	73.6	69.8
Underwriting and general and administrative expenses	36.5	35.7	111.8	101.8
Interest and financing expenses	0.9	1	4.9	1.3
Other Expenses			9.4
Operating Expenses	179.5	175.7	515.2	477.6
Net (loss) income before income taxes	20.8	26.1	97.5	16.5
Cerity Segment [Member]
Segment Reporting Information [Line Items]
Premiums Written, Gross	2.2	1.5	5.1	3.6
Premiums Written, Net	2.2	1.5	5.1	3.6
Net premiums earned	1.9	0.8	4.9	2
Net investment income	1.6	1.2	5	2.7
Net realized and unrealized (losses) gains on investments	(0.4)	(0.3)	(0.2)	(1.6)
Other income (loss)	0	0	0	0
Revenues	(3.1)	(1.7)	(9.7)	(3.1)
Losses and loss adjustment expenses	1.3	0.6	3.2	1.3
Commission expense	0.1	0.1	0.2	0.1
Underwriting and general and administrative expenses	3.6	3.4	12	9.9
Interest and financing expenses	0	0	0	0
Other Expenses			0
Operating Expenses	5	4.1	15.4	11.3
Net (loss) income before income taxes	(1.9)	(2.4)	(5.7)	(8.2)
Corporate Segment
Segment Reporting Information [Line Items]
Premiums Written, Gross	0	0	0	0
Premiums Written, Net	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	0.9	1.1	3	2.4
Net realized and unrealized (losses) gains on investments	(0.8)	(0.2)	(0.2)	(7.9)
Other income (loss)	0	0	0	0
Revenues	(0.1)	0.9	(2.8)	5.5
Losses and loss adjustment expenses	(1.9)	(2.1)	(5.9)	(6.3)
Commission expense	0	0	0	0
Underwriting and general and administrative expenses	3.4	2.8	9.9	8.9
Interest and financing expenses	0.1	0.1	0.3	0.3
Other Expenses			0
Operating Expenses	1.6	0.8	4.3	2.9
Net (loss) income before income taxes	$ (1.5)	$ 0.1	$ (1.5)	$ (8.4)

Segment Reporting Geographic In

Segment Reporting Geographic Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Revenue, Major Customer [Line Items]
Segment Reporting, Disclosure of Major Customers	10
CALIFORNIA
Revenue, Major Customer [Line Items]
Premiums In Force	$ 301.9	$ 279.7	$ 272.9	$ 258.4
Policies In force	43,272	42,876	42,934	40,704
FLORIDA
Revenue, Major Customer [Line Items]
Premiums In Force	$ 55.4	$ 49.4	$ 46.8	$ 41.1
Policies In force	10,052	9,417	9,034	7,989
NEW YORK
Revenue, Major Customer [Line Items]
Premiums In Force	$ 31.1	$ 27.3	$ 26.4	$ 24.5
Policies In force	7,570	7,497	7,577	7,307
AllOtherStates [Member]
Revenue, Major Customer [Line Items]
Premiums In Force	$ 287.6	$ 266.1	$ 260.8	$ 247.4
Policies In force	65,226	61,566	60,602	55,350
UNITED STATES
Revenue, Major Customer [Line Items]
Premiums In Force	$ 676	$ 622.5	$ 606.9	$ 571.4
Policies In force	126,120	121,356	120,147	111,350
Final audit policies in-force	0	0	0	0
Final audit premium	$ 46.1	$ 42.5	$ 42.2	$ 42.3
Total in-force policies, includingfinal audit	126,120	121,356	120,147	111,350
Total in-force, including final audit premium	$ 722.1	$ 665	$ 649.1	$ 613.7