Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (7,461)	$ 17,019	$ 92,912
Other comprehensive income, net of tax:
Change in unrealized gain (loss) on available-for-sale investment securities, net of taxes of $28, $7, and $22, respectively	(44)	10	1,128
Comprehensive (loss) income	$ (7,505)	$ 17,029	$ 94,040