Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ (243)	$ 392
Effective income tax expense (benefit) rate	(10.30%)	15.60%
Unrecognized tax benefits	$ 8,900		$ 5,300
Expencted reduction in unrecognized tax benefits	$ 3,400