Reconciliation of Unrecognized Tax Benefits (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized tax benefits at January 1, 2016	$ 1,289
Gross increases - tax positions in prior period	118
Unrecognized tax benefits at December 31, 2016	$ 1,407