Employee Benefit Plans (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) item	Jan. 01, 2019 USD ($)	Jan. 02, 2018 USD ($)
Employee Benefit Plans
Minimum number of investment options available to participating plan members | item	1
Accrued liability for self-insured benefit plans	$ 10.8	$ 10.4
401(k) Plan
Employee Benefit Plans
Expense recognized	1.2	1.0	$ 1.0
ESP
Employee Benefit Plans
Expense recognized	$ 1.2	$ 1.3	$ 1.0