Schedule II - Condensed Financial Information of Registrant (Parent Company) - Condensed Statements 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 earnings	$ 304,611	$ 583,411	$ 279,354
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses	(32,518)	(588,515)	(64,222)
Depreciation	8,545	7,981	7,394
Other items, net	24,947	(20,467)	14,141
Changes in investment in unconsolidated investees:
Undistributed earnings	(9,610)	(9,853)	(37,060)
Dividends received	0	0	0
Net cash provided by operating activities	464,257	250,448	384,905
Purchase of:
Fixed income securities, available-for-sale	(662,070)	(2,053,359)	(733,811)
Other	(10,786)	(5,704)	(11,428)
Sale of:
Fixed income securities - available-for-sale	50,135	53,300	63,811
Equity method investee	14,284	686,666
Property and equipment	27	375
Call or maturity of:
Fixed income securities - available-for-sale	504,168	1,393,674	376,750
Net purchase of short-term investments	(98,694)	(36,229)
Net cash provided by (used in) investing activities	(211,803)	48,879	(274,826)
Cash Flows from Financing Activities
Proceeds from stock option exercises	1,245	(465)	1,838
Proceeds from issuance of debt	100,000		50,000
Repayment of debt	(200,000)
Net cash used in financing activities	(238,848)	(365,313)	(83,492)
Net increase (decrease) in cash	13,606	(65,986)	26,587
Cash at the beginning of the period	22,818	88,804	62,217
Cash at end of year	36,424	22,818	88,804
Parent Company
Cash flows from operating activities:
Net earnings	3,827	448,284	4,902
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses	(14,134)	(570,888)	625
Depreciation	35	64	68
Other items, net	1,350	1,403	3,966
Change in:
Affiliate balances receivable/payable	(821)	(724)	(3,404)
Federal income taxes	(1,409)	(19,484)	5,901
Changes in investment in unconsolidated investees:
Undistributed earnings		(372)	(22,786)
Net cash provided by operating activities	(11,152)	(141,717)	(10,728)
Purchase of:
Fixed income securities, available-for-sale	(89,501)	(1,356,177)	(33,373)
Other	(1,832)	(1,420)	(2,904)
Sale of:
Fixed income securities - available-for-sale		1,373	5,306
Equity method investee	14,134	686,566
Property and equipment		298
Other	54	221	1,245
Call or maturity of:
Fixed income securities - available-for-sale	263,939	1,192,050	2,878
Net purchase of short-term investments	(74,696)	(2,229)
Cash dividends received-subsidiaries	145,000	13,000	180,000
Net cash provided by (used in) investing activities	257,098	533,682	153,152
Cash Flows from Financing Activities
Proceeds from stock option exercises	1,245	(465)	1,838
Proceeds from issuance of debt	50,000
Repayment of debt	(150,000)
Cash dividends paid	(152,508)	(397,323)	(147,422)
Other	5,314	5,441	4,212
Net cash used in financing activities	(245,949)	(392,347)	(141,372)
Net increase (decrease) in cash	(3)	(382)	1,052
Cash at the beginning of the period	1,051	1,433	381
Cash at end of year	$ 1,048	$ 1,051	$ 1,433