Income Taxes - (Benefit) Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Federal:
Current	$ (92)		$ 30
Deferred	(398)	$ (10,665)	229	$ (13,627)
Gross Federal	(490)	(10,665)	259	(13,627)
State:
Current	(70)	60	10	159
Deferred	(17)	(103)		(109)
Gross State	(87)	(43)	10	50
Income tax expense (benefit)	$ (577)	$ (10,708)	$ 269	$ (13,577)