Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (69,707)	$ 26,144	$ 8,587
Other comprehensive (loss) income:
Unrealized loss on available-for-sale securities	0	(5,485)	0
Reclassification of other-than-temporary loss on available-for-sale securities included in net income	0	5,485	0
Comprehensive (loss) income	$ (69,707)	$ 26,144	$ 8,587