Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Current:
Federal		$ (107)
State		(5)
Total current		(112)
Deferred:
Federal	$ (1,818)	(495)
State	(8)	(22)
Total deferred	(1,826)	(517)
Total income tax benefit	$ (1,826)	$ (629)