Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 218,425	$ 287,449
Cash flows from investing activities:
Proceeds from Sale and Maturity of Fixed-Maturity Investments Available-for-sale	737,054	537,679
Proceeds from Sale of Available-for-sale Securities, Equity	23,423	74,868
Proceeds from Sale of Trading Securities Held-for-investment	176,448	178,227
Proceeds from Redemption of Fixed-Maturity Investments Available-for-sale	377,219	220,126
Proceeds from Redemption of Trading Securities Held-for-investment	70,161	106,589
Purchases of Fixed-Maturity Investments Available-for-sale	(1,491,083)	(1,419,431)
Equity securities available for sale	(195,297)	(830)
Sales, Redemptions and (Purchases) of Short-term Investments	251,509	241,579
Sales, Redemptions and (Purchases) of Other assets and other invested assets, net	596	2,390
Purchases of property and equipment, net	(25,173)	(28,252)
Acquisitions, net of cash acquired	(86)	0
Net cash provided by (used in) investing activities	(75,229)	(87,055)
Cash flows from financing activities:
Dividends paid	(1,614)	(1,568)
Issuance of long-term debt, net	443,250	343,417
Purchases and redemptions of long-term debt	(591,918)	(445,069)
Proceeds from termination of capped calls	4,109	0
Issuance of common stock	3,283	343
Purchase of common shares	(6)	(100,188)
Change in payable under securities lending program	36,782	0
Excess tax benefits from share-based awards (Note 1)	0	115
Repayment of other borrowings	(207)	(292)
Net cash provided by (used in) financing activities	(106,321)	(203,242)
Effect of exchange rate changes on cash and restricted cash	116	(382)
Increase (decrease) in cash and restricted cash	36,991	(3,230)
Cash and restricted cash, beginning of period	61,814	59,898
Cash and restricted cash, end of period	$ 98,805	$ 56,668