Income Taxes - Benefit for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Federal:
Current		$ 20	$ 228
Deferred	$ (16,024)	(893)	(19,098)
Gross Federal	(16,024)	(873)	(18,870)
State:
Current	328	255	650
Deferred	(152)	(24)	(125)
Gross State	176	231	525
Income tax expense (benefit)	$ (15,848)	$ (642)	$ (18,345)