Schedule II - Condensed Financial Information of Registrant (Parent Company) - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net earnings	$ 583,411	$ 279,354	$ 157,091
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses	(588,515)	(64,222)	(17,885)
Depreciation	7,981	7,394	7,432
Other items, net	(20,467)	14,141	10,460
Changes in investment in unconsolidated investees:
Undistributed earnings	(9,853)	(37,060)	(20,233)
Dividends received	0	0	4,675
Net cash provided by operating activities	250,448	384,905	263,259
Purchase of:
Fixed income securities, available-for-sale	(2,053,359)	(733,811)	(518,362)
Other	(5,704)	(11,428)	(12,851)
Sale of:
Fixed income securities - available-for-sale	53,300	63,811	84,587
Equity method investments	686,666
Property and equipment	375
Call or maturity of:
Fixed income securities - available-for-sale	1,393,674	376,750	283,107
Net purchase of short-term investments	(36,229)
Net cash provided by (used in) investing activities	48,879	(274,826)	(167,987)
Cash Flows from Financing Activities
Proceeds from stock option exercises	(465)	1,838	8,648
Net cash used in financing activities	(365,313)	(83,492)	(79,258)
Net increase (decrease) in cash	(65,986)	26,587	16,014
Cash at the beginning of the year	88,804	62,217	46,203
Cash at the end of the year	22,818	88,804	62,217
Parent Company
Cash flows from operating activities:
Net earnings	448,284	4,902	(2,702)
Adjustments to reconcile net losses to net cash provided by (used in) operating activities:
Net realized (gains) losses	(570,888)	625	(501)
Depreciation	64	68	67
Other items, net	1,403	3,966	2,270
Change in:
Affiliate balances receivable/payable	(724)	(3,404)	1,246
Federal income taxes	(19,484)	5,901	1,399
Changes in investment in unconsolidated investees:
Undistributed earnings	(372)	(22,786)	(10,368)
Net cash provided by operating activities	(141,717)	(10,728)	(8,589)
Purchase of:
Fixed income securities, available-for-sale	(1,356,177)	(33,373)	(24,950)
Other	(1,420)	(2,904)	(346)
Sale of:
Fixed income securities - available-for-sale	1,373	5,306	3,767
Equity method investments	686,566
Property and equipment	298
Other	221	1,245
Call or maturity of:
Fixed income securities - available-for-sale	1,192,050	2,878	3,492
Net purchase of short-term investments	(2,229)
Cash dividends received-subsidiaries	13,000	180,000	110,000
Net cash provided by (used in) investing activities	533,682	153,152	91,963
Cash Flows from Financing Activities
Proceeds from stock option exercises	(465)	1,838	8,648
Cash dividends paid	(397,323)	(147,422)	(95,793)
Other	5,441	4,212	3,802
Net cash used in financing activities	(392,347)	(141,372)	(83,343)
Net increase (decrease) in cash	(382)	1,052	31
Cash at the beginning of the year	1,433	381	350
Cash at the end of the year	$ 1,051	$ 1,433	$ 381