Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits, beginning of year		$ 9	$ 108
Increase in tax position in current year	$ 0	0	0
Settlement/Expiration of statute	$ 0	0	0
De-recognition through administrative policy		$ (9)	(99)
Gross unrecognized tax benefits, end of year			$ 9