Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income (loss)	$ (27,342)	$ 98,112	$ 49,130	$ 164,361
Unrealized holding gains (losses) arising during the period
Unrealized holding gains (losses) arising during the period	20,239	40,297	27,606	79,671
Less: Reclassification adjustment for net gains (losses) included in net income (loss)	(1,167)	758	(2,798)	(1,399)
Net unrealized gains (losses) on investments	21,406	39,539	30,404	81,070
Net foreign currency translation adjustments	74	(225)	108	(310)
Net actuarial gains (losses)	0	0	0	(178)
Other comprehensive income (loss), net of tax	21,480	39,314	30,512	80,582
Comprehensive income (loss)	$ (5,862)	$ 137,426	$ 79,642	$ 244,943