Consolidated Statement of Stockholders' Equity - 3 months ended Mar. 31, 2016 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2015	$ 1,096,148	$ 1,793	$ 357,829	$ (155,801)	$ 868,723	$ 23,604
Beginning balance (in shares) at Dec. 31, 2015	17,942,269	17,942,269		3,511,380
Net income	$ 22,932				22,932
Changes in comprehensive income:
Change in net unrealized gain (loss) on investments	23,206					23,206
Change in net non-credit other-than-temporary impairment losses	(71)					(71)
Change in foreign currency translation gain (loss)	(346)					(346)
Other comprehensive income (loss)	22,789					22,789
Shares issued under stock plan	(2,916)	$ 10	(2,926)
Shares issued under stock plan (in shares)		100,205
Share-based compensation	4,926		4,926
Ending balance at Mar. 31, 2016	$ 1,143,879	$ 1,803	$ 359,829	$ (155,801)	$ 891,655	$ 46,393
Ending balance (in shares) at Mar. 31, 2016	18,042,474	18,042,474		3,511,380