Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
State	$ (351)	$ (378)	$ (361)
Total current expense	(351)	(378)	(361)
Deferred:
Income tax expense	$ (351)	$ (378)	$ (361)