Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (112,689)	$ (120,741)	$ (92,189)
Other comprehensive income (loss):
Unrealized gain on available-for-sale securities, net of income tax expense of $0.2 million, $0, and $9.7 million for the years ended December 31, 2019, 2018, and 2017, respectively (see Note 3(a))	622	0	16,039
Foreign currency translation adjustments	(418)	(2,490)	1,539
Other comprehensive income (loss)	204	(2,490)	17,578
Total comprehensive loss	$ (112,485)	$ (123,231)	$ (74,611)