CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 30,085	$ 15,906	$ (843)
Other comprehensive income (loss), net of reclassification adjustments:
Unrealized gains (losses) on investments, net	(72)	66	(24)
Tax benefit (expense) on unrealized gains (losses) on investments, net	39	(30)	9
Unrealized gains on cash flow hedges	2,979	0	0
Tax expense on unrealized gains on cash flow hedges	(1,136)	0	0
Other comprehensive income (loss), net of tax	1,810	36	(15)
Comprehensive income (loss)	$ 31,895	$ 15,942	$ (858)