Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 217,778	$ 118,447
Cash flows from investing activities:
Proceeds from Sales of Fixed-Maturity Investments Available-for-sale	435,709	224,597
Proceeds from Sales of Trading Securities	70,083	11,964
Proceeds from Sales of Equity Securities	33,278	55,795
Proceeds from Redemption of Fixed-Maturity Investments Available for sale	79,915	94,356
Proceeds from Redemptions of Trading securities	23,293	17,890
Purchases of Fixed-Maturity Investments Available-for-sale	(275,531)	(482,260)
Purchases of Equity Securities	(19,767)	(19,994)
Sales, Redemptions and (Purchases) of Short-term Investments, Net	(526,013)	(17,217)
Sales, Redemptions and (Purchases) of Other assets and other invested assets, net	349	92
Purchases of property and equipment, net	(6,659)	(4,702)
Acquisitions, net of cash acquired	0	(261)
Net cash provided by (used in) investing activities	(185,343)	(119,740)
Cash flows from financing activities:
Dividends paid	(534)	(540)
Issuance of common stock	363	663
Purchase of common shares	(31,774)	(10,003)
Credit facility commitment fees paid	(234)	(185)
Change in secured borrowings, net (with terms less than 3 months)	21,534	38,719
Proceeds from secured borrowings (with terms greater than 3 months)	6,000	6,550
Payments of secured borrowings (with terms greater than 3 months)	(7,000)	0
Repayment of other borrowings	(38)	(50)
Net cash provided by (used in) financing activities	(11,683)	35,154
Effect of exchange rate changes on cash and restricted cash	0	(1)
Increase (decrease) in cash and restricted cash	20,752	33,860
Cash and restricted cash, beginning of period	107,002	96,244
Cash and restricted cash, end of period	$ 127,754	$ 130,104