Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory rate			21.00%		35.00%
Additional provision on re-measurement of deferred tax assets			$ 1,600
Income tax expense (benefit)	$ (7,051)	$ (3,355)	$ 1,114	$ (4,880)
Effective income tax rate	91.40%		5.90%