Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 153,029	$ 155,800
Cash Flows from Investing Activities
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale	154,423	533,019
Proceeds from Sales of Trading Securities	7,952	9,936
Proceeds from Sales of Equity Securities	1,839	59,339
Proceeds from Redemption of Fixed-Maturity Investments Available for sale	295,707	151,559
Proceeds from Redemptions of Trading securities	8,965	16,427
Purchases of Fixed-maturities Available-for-sale	(481,051)	(619,024)
Purchases of Equity Securities	(38,110)	(60,309)
Sales, Redemptions and (Purchases) of Short-term Investments, Net	(32,311)	(72,220)
Payments for (Proceeds from) Other Investing Activities	2,721	2,347
Proceeds from sale of subsidiary, net of cash sold	0	15,869
Payments for (Proceeds from) Productive Assets	(2,073)	(4,950)
Net cash provided by (used in) investing activities	(81,938)	31,993
Cash Flows from Financing Activities
Dividends and dividend equivalents paid	(24,095)	(25,138)
Issuance of common stock	340	1,447
Repurchases of common shares	(8,637)	(226,305)
Credit facility commitment fees paid	(234)	(237)
Change in secured borrowings, net (with terms three months or less)	16,152	(2,854)
Proceeds from secured borrowings (with terms greater than 3 months)	3,000	59,995
Payments of secured borrowings (with terms greater than 3 months)	(28,000)	(29,011)
Repayments of other borrowings	0	(39)
Net cash provided by (used in) financing activities	(41,474)	(222,142)
Increase (decrease) in cash and restricted cash	29,617	(34,349)
Cash and restricted cash, beginning of period	94,146	96,274
Cash and restricted cash, end of period	$ 123,763	$ 61,925