Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net income	$ 114,486	$ 76,472
Unrealized holding gains (losses) arising during the period
Unrealized holding gains (losses) arising during the period	(60,643)	7,367
Less: Reclassification adjustment for net gains (losses) included in net income	(3,132)	(1,631)
Net unrealized gains (losses) on investments	(57,511)	8,998
Unrealized foreign currency translation adjustments	3	34
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an ASU for Financial Instruments, Net of Tax	224	0
Cumulative effect of adopting the accounting standard update for the reclassification of certain tax effects	2,724	0
Other comprehensive income (loss), net of tax	(54,560)	9,032
Comprehensive income	$ 59,926	$ 85,504