CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (27,171)	$ (19,168)
Other comprehensive loss, net of tax:
Net change in unrealized gain on available-for-sale investments	129	40
Foreign currency translation gain (loss)	733	(440)
Net change in unrealized gain on derivative instruments	2,610
Comprehensive loss	$ (23,699)	$ (19,568)