Income Taxes - Reconciliation of Gross Amount of Unrecognized Tax Benefits Excluding Accrued Interest and Penalties (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 at beginning of period	$ 409	$ 434	$ 627
Settlements	0	0	(176)
Lapse of statute of limitations	0	(25)	(17)
Balance at end of period	$ 409	$ 409	$ 434