Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 159,000	$ 105,000	$ 62,000
(Reduction) additional provision and interest related to prior years, net	(4,000)	70,000	43,000
Resolution of matters during the period	(1,000)	(16,000)	0
Balance at end of period	$ 154,000	$ 159,000	$ 105,000