Income Taxes - Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Beginning Balance	$ 1,154	$ 672	$ 353
Additions based on tax positions taken during the current period	761	401	222
Reductions based on tax positions taken during the prior period	(42)	(50)	(47)
Additions based on tax positions taken during a prior period	409	131	144
Ending Balance	$ 2,282	$ 1,154	$ 672