Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss) including noncontrolling interests in operating subsidiaries	$ (104,848)	$ 21,684
Other comprehensive income (loss):
Unrealized loss on short-term investments	0	(40)
Unrealized gain on foreign currency translation	88	58
Add: reclassification adjustment for losses included in net income	0	(30)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(104,760)	21,672
Net (income) loss attributable to noncontrolling interests in subsidiaries	181	(496)
Comprehensive income	$ (104,941)	$ 22,168