Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (18,709)	$ (17,455)	$ (62,144)	$ (51,070)
Other comprehensive income:
Unrealized gain on available-for-sale securities, net of income tax expense of $2,068, $342, and $2,068, $872 for the three and nine months ended September 30, 2017 and 2016, respectively.	5,047	465	3,903	2,975
Foreign currency translation adjustments	405	96	1,349	254
Other comprehensive income	5,452	561	5,252	3,229
Total comprehensive loss	$ (13,257)	$ (16,894)	$ (56,892)	$ (47,841)