Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 305,291	$ 338,129
Cash Flows from Investing Activities:
Proceeds from Sales of Fixed-Maturity Investments Available for sale	735,154	568,351
Proceeds from Sales of Trading Securities	11,602	111,713
Proceeds from Sales of Equity Securities	75,793	39,818
Proceeds from Redemption of Fixed-Maturity Investments Available for sale	271,477	184,464
Proceeds from Redemptions of Trading securities	17,810	35,852
Purchases of Fixed-Maturity Investments Available for sale	(1,216,333)	(665,882)
Purchases of Equity Securities	(65,427)	(31,853)
Sales, Redemptions and (Purchases) of Short-term Investments, Net	(418,744)	(372,540)
Sales, Redemptions and (Purchases) of Other assets and other invested assets, net	2,346	490
Proceeds from sale of a subsidiary, net of cash sold	16,481	0
Purchases of property and equipment, net	(10,594)	(15,207)
Net cash provided by (used in) investing activities	(580,435)	(144,794)
Cash Flows from Financing Activities:
Dividends and dividend equivalents paid	(49,301)	(1,053)
Issuance of senior notes, net	516,083	442,937
Repayments and repurchases of senior notes	0	(508,017)
Issuance of common stock	1,480	1,268
Repurchases of common shares	(226,305)	(188,817)
Credit facility commitment fees paid	(1,754)	(471)
Change in secured borrowings, net (with terms three months or less)	(17,535)	11,563
Proceeds from secured borrowings (with terms greater than 3 months)	106,960	36,000
Payments of secured borrowings (with terms greater than 3 months)	(66,013)	(14,550)
Repayments of other borrowings	(79)	(75)
Net cash provided by (used in) financing activities	263,536	(221,215)
Increase (decrease) in cash and restricted cash	(11,608)	(27,884)
Cash and restricted cash, beginning of period	96,274	107,002
Cash and restricted cash, end of period	84,666	79,118
Effect of Exchange Rate on Cash and Cash Equivalents	$ 0	$ (4)

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