Employee Benefit Plans (Details) $ in Millions	12 Months Ended
	Jan. 01, 2019 USD ($) item	Jan. 02, 2018 USD ($)	Jan. 03, 2017 USD ($)
Employee Benefit Plans
Minimum number of investment options available to participating plan members | item	1
Maximum amount of eligible bonuses that may be deferred by participating staff members under the ESP (as a percent)	100.00%
Accrued liability for self-insured benefit plans	$ 10.4	$ 8.8
401(k) Plan
Employee Benefit Plans
Expense recognized	1.0	1.0	$ 0.9
ESP
Employee Benefit Plans
Expense recognized	$ 1.3	$ 1.0	$ 1.0