Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 275,896	$ 305,291
Cash Flows from Investing Activities
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale	329,072	735,154
Proceeds from Sales of Trading Securities	7,952	11,602
Proceeds from Sales of Equity Securities	4,440	75,793
Proceeds from Redemption of Fixed-Maturity Investments Available for sale	619,265	271,477
Proceeds from Redemptions of Trading securities	10,606	17,810
Purchases of Fixed-maturities Available-for-sale	(944,618)	(1,216,333)
Purchases of Equity Securities	(61,235)	(65,427)
Sales, Redemptions and (Purchases) of Short-term Investments, Net	(41,925)	(418,744)
Payments for (Proceeds from) Other Investing Activities	5,043	2,346
Proceeds from sale of subsidiary, net of cash sold	0	16,481
Payments for (Proceeds from) Productive Assets	(4,993)	(10,594)
Net cash provided by (used in) investing activities	(76,393)	(580,435)
Cash Flows from Financing Activities
Dividends and dividend equivalents paid	(52,036)	(49,301)
Issuance of senior notes, net	0	516,083
Issuance of common stock	1,112	1,480
Repurchases of common shares	(98,695)	(226,305)
Credit facility commitment fees paid	(471)	(1,754)
Change in secured borrowings, net (with terms three months or less)	4,348	(17,535)
Proceeds from secured borrowings (with terms greater than 3 months)	32,000	106,960
Payments of secured borrowings (with terms greater than 3 months)	(42,000)	(66,013)
Repayments of other borrowings	0	(79)
Net cash provided by (used in) financing activities	(155,742)	263,536
Increase (decrease) in cash and restricted cash	43,761	(11,608)
Cash and restricted cash, beginning of period	94,146	96,274
Cash and restricted cash, end of period	$ 137,907	$ 84,666