Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits Excluding Interest and Penalties (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Uncertain tax positions, Beginning balance	$ 7,470	$ 1,180	$ 1,180
Additions for current year tax positions	0	0	0
Additions for prior year tax positions	0	7,470	0
Reductions for prior year tax positions	0	0	0
Settlements	0	(1,180)	0
Reductions due to lapse of applicable statute of limitation	0	0	0
Uncertain tax positions, Ending balance	$ 7,470	$ 7,470	$ 1,180