Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2016	Sep. 30, 2015	Sep. 28, 2016	Sep. 30, 2015	Dec. 30, 2015
Property Plant And Equipment [Abstract]
Depreciation expense	$ 4.1	$ 3.3	$ 11.8	$ 9.6
Gross value of assets under capital leases for buildings and improvements	1.6		1.6		$ 1.6
Accumulated depreciation of assets under capital leases	1.5		1.5		$ 1.5
Capital expenditures	12.1		26.5
Capital expenditures for restaurant remodeling	0.1		1.6
Capital expenditures for new restaurants	$ 10.8		$ 20.8