Investments - Available for Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Less: loaned securities	$ 139,121	$ 203,693
Total fixed-maturities, available for sale, Amortized Cost	5,511,501	5,599,111
Total fixed-maturities available for sale, Fair Value	5,074,920	5,188,228
Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,648,583	5,734,767
Total fixed-maturities, available for sale, Amortized Cost	5,511,501	5,599,111
Gross Unrealized Gains	16,565	24,174
Gross Unrealized Losses	(460,376)	(443,531)
Fair Value	5,204,772	5,315,410
Total fixed-maturities available for sale, Fair Value	5,074,920	5,188,228
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	160,509	171,194
Gross Unrealized Gains	0	93
Gross Unrealized Losses	(32,177)	(26,891)
Fair Value	128,332	144,396
State and municipal obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	167,114	158,539
Gross Unrealized Gains	40	283
Gross Unrealized Losses	(18,263)	(16,037)
Fair Value	148,891	142,785
Corporate bonds and notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,878,705	2,876,175
Gross Unrealized Gains	5,261	12,286
Gross Unrealized Losses	(277,535)	(259,177)
Fair Value	2,606,431	2,629,284
RMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,104,721	1,089,919
Gross Unrealized Gains	6,965	8,250
Gross Unrealized Losses	(100,056)	(84,098)
Fair Value	1,011,630	1,014,071
CMBS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	438,139	605,029
Gross Unrealized Gains	51	51
Gross Unrealized Losses	(26,191)	(46,697)
Fair Value	411,999	558,383
CLO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	411,328	494,339
Gross Unrealized Gains	983	63
Gross Unrealized Losses	(849)	(6,553)
Fair Value	411,462	487,849
Other ABS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	442,620	286,988
Gross Unrealized Gains	1,556	1,608
Gross Unrealized Losses	(5,305)	(4,037)
Fair Value	438,871	284,559
Foreign government and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		5,128
Gross Unrealized Gains		0
Gross Unrealized Losses		(41)
Fair Value		5,087
Mortgage insurance-linked notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,447	47,456
Gross Unrealized Gains	1,709	1,540
Gross Unrealized Losses	0	0
Fair Value	47,156	48,996
Loaned securities, amortized cost \| Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Less: loaned securities	137,082	135,656
Loaned securities, fair value
Debt Securities, Available-for-sale [Line Items]
Less: loaned securities	130,000
Loaned securities, fair value \| Total fixed-maturities available for sale
Debt Securities, Available-for-sale [Line Items]
Less: loaned securities	$ 129,852	$ 127,182

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Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, Before Tax, Including Loaned Securities

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