Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance — Beginning of the year	$ 489	$ 27	$ 189
Gross increase — tax positions in prior periods	40	445	0
Gross decreases — tax positions in prior periods	0	0	(170)
Gross increases — current period tax positions	103	44	8
Lapse of statute of limitations	(4)	(27)	0
Balance — End of the year	$ 628	$ 489	$ 27