Schedule II - Financial Information of Registrant - Parent Company Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ 529,434	$ 388,298	$ 557,112
Proceeds from sales of:
Trading securities	9,123	8,868	7,952
Proceeds from redemptions of:
Fixed-maturities available for sale	498,081	789,929	1,225,626
Purchases of:
Fixed-maturities available for sale	(933,264)	(1,414,966)	(1,980,155)
Equity securities	(8,334)	(24,637)	(105,649)
Sales, redemptions and (purchases) of:
Short-term investments, net	(251,662)	150,694	68,083
Other assets and other invested assets, net	(45)	(6,887)	6,126
Net cash provided by (used in) investing activities	(300,842)	(5,175)	(1,862)
Cash flows from financing activities
Dividends and dividend equivalents paid	(145,908)	(135,437)	(103,298)
Issuance of common stock	1,755	1,341	1,382
Repurchases of common stock	(133,314)	(400,195)	(399,100)
Credit facility commitment fees paid	(904)	(814)	(3,325)
Change in secured borrowings, net (with terms three months or less)	2,122	60,270	1,057
Net cash provided by (used in) financing activities	(265,087)	(479,183)	(496,776)
Increase (decrease) in cash and restricted cash	(36,495)	(96,060)	58,474
Cash and restricted cash, beginning of period	56,560	152,620	94,146
Cash and restricted cash, end of period	20,065	56,560	152,620
Parent Company
Cash flows from operating activities
Net cash provided by (used in) operating activities	194,607	(71)	66,317
Proceeds from sales of:
Fixed-maturities available for sale	129,650	56,934	195,452
Trading securities	0	8,868	0
Equity securities	60,755	0	0
Proceeds from redemptions of:
Fixed-maturities available for sale	168,639	194,859	301,788
Purchases of:
Fixed-maturities available for sale	(84,313)	(29,039)	(156,344)
Equity securities	(3,690)	(2,500)	0
Sales, redemptions and (purchases) of:
Short-term investments, net	(135,657)	188,149	113,939
Other assets and other invested assets, net	(10,664)	(3,851)	(864)
Capital distributions from subsidiaries	7,000	32,512	44,951
Capital contributions to subsidiaries	(49,750)	(8,000)	(43,250)
Net cash provided by (used in) investing activities	81,970	437,932	455,672
Cash flows from financing activities
Dividends and dividend equivalents paid	(145,908)	(135,437)	(103,298)
Issuance of common stock	1,755	1,341	1,382
Repurchases of common stock	(133,314)	(400,195)	(399,100)
Credit facility commitment fees paid	(904)	(814)	(3,325)
Net cash provided by (used in) financing activities	(276,249)	(474,835)	(503,284)
Increase (decrease) in cash and restricted cash	328	(36,974)	18,705
Cash and restricted cash, beginning of period	1,872	38,846	20,141
Cash and restricted cash, end of period	2,200	1,872	38,846
Cash distributions received from consolidated subsidiaries	191,000	50,000	85,000
Dividends received from consolidated subsidiaries	$ 218,000	$ 888,000	$ 92,000