Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 13,744	$ (20,852)	$ (2,074)	$ (44,398)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net of income tax benefit of $960, and $0 for the three and six months ended June 30, 2017	0	(2,951)	0	(1,144)
Cumulative effect of ASU 2016-01 adoption on January 1, 2018 for unrealized gains on equity securities, net of income tax; recorded as a reclassification to accumulated deficit (see Note 3(a))	0	0	(17,211)	0
Foreign currency translation adjustments	(2,269)	792	(1,876)	944
Other comprehensive loss	(2,269)	(2,159)	(19,087)	(200)
Total comprehensive income (loss)	$ 11,475	$ (23,011)	$ (21,161)	$ (44,598)