Summary of Significant Accounting Policies - Property and Equipment At Cost and Depreciable Useful Lives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Property, Plant and Equipment [Line Items]
Property and equipment	$ 291.8	$ 270.0
Depreciation expense	21.8	20.7	$ 21.4
Land
Property, Plant and Equipment [Line Items]
Property and equipment	3.8	3.8
Work in process
Property, Plant and Equipment [Line Items]
Property and equipment	5.3	0.8
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 64.9	61.1
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment	$ 154.2	145.0
Computer hardware and software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer hardware and software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	12 years
Equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	$ 37.9	33.8
Estimated useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 25.7	$ 25.5
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years