Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 403,304	$ 498,756
Cash Flows from Investing Activities
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale	536,387	894,998
Proceeds from Sales of Trading Securities	7,952	11,602
Proceeds from Sales of Equity Securities	29,289	77,445
Proceeds from Redemption of Fixed-Maturity Investments Available for sale	917,027	443,723
Proceeds from Redemptions of Trading securities	11,703	22,112
Purchases of Fixed-maturities Available-for-sale	(1,413,445)	(2,099,281)
Purchases of Equity Securities	(102,956)	(69,206)
Sales, Redemptions and (Purchases) of Short-term Investments, Net	(17,474)	(21,797)
Payments for (Proceeds from) Other Investing Activities	6,253	989
Proceeds from sale of subsidiary, net of cash sold	0	16,481
Purchases of property and equipment	(8,720)	(14,723)
Net cash provided by (used in) investing activities	(33,984)	(737,657)
Cash Flows from Financing Activities
Dividends and dividend equivalents paid	(78,165)	(73,365)
Issuance of senior notes, net	0	515,567
Issuance of common stock	1,225	1,505
Repurchases of common stock	(251,482)	(226,305)
Credit facility commitment fees paid	(710)	(1,993)
Change in secured borrowings, net (with terms three months or less)	38,241	(19,191)
Proceeds from secured borrowings (with terms greater than 3 months)	32,000	138,909
Payments of secured borrowings (with terms greater than 3 months)	(48,000)	(105,977)
Repayments of other borrowings	0	(79)
Net cash provided by (used in) financing activities	(306,891)	229,071
Increase (decrease) in cash and restricted cash	62,429	(9,830)
Cash and restricted cash, beginning of period	94,146	96,274
Cash and restricted cash, end of period	$ 156,575	$ 86,444