Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, beginning of period at Dec. 31, 2014		$ 522	$ 353,337	$ 795,740	$ 95,527
Repurchases of common stock		(41)	(187,180)
Share-based compensation			28,073
Net issuance of common stock		5	(5)
Adjustments to paid-in capital, other			1,089
Net income	$ 141,924			141,924
Dividends				(24,915)
Change in foreign currency translation adjustment, net of income tax expense (benefit)					(33,365)
Change in net unrealized investment gains (losses) not-other-than temporarily impaired, net of income tax expense (benefit)					(24,419)
Change in net unrealized investment losses other-than-temporarily impaired, net of income tax expense (benefit)					389
Balance, end of period at Sep. 30, 2015	1,146,681	486	195,314	912,749	38,132
Balance, beginning of period at Dec. 31, 2015	1,145,772	483	180,250	952,804	12,235
Repurchases of common stock		(29)	(135,298)
Share-based compensation			21,564
Net issuance of common stock		6	(6)
Net income	162,540			162,540
Dividends				(24,956)
Change in foreign currency translation adjustment, net of income tax expense (benefit)					11,574
Change in net unrealized investment gains (losses) not-other-than temporarily impaired, net of income tax expense (benefit)					39,720
Change in net unrealized investment losses other-than-temporarily impaired, net of income tax expense (benefit)					6
Balance, end of period at Sep. 30, 2016	$ 1,220,893	$ 460	$ 66,510	$ 1,090,388	$ 63,535