Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 30, 2017	Sep. 29, 2018	Dec. 30, 2017
Income Tax Disclosure [Abstract]
Net unrecognized tax benefits		$ 2,500,000
Unrecognized tax benefits which would impact effective tax rate if recognized		2,200,000
Accrued interest and penalties related to uncertain tax positions		$ 700,000
U.S. corporate income tax rate		21.00%	35.00%
Net tax expense due to TCJA	$ 4,400,000
Adjustment to provisional expense due to TCJA		$ 0