Summary of Significant Accounting Policies - Property and Equipment At Cost and Depreciable Useful Lives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2023	Jan. 02, 2022
Property, Plant and Equipment [Line Items]
Property and equipment	$ 138.1	$ 166.8
Total property, plant and equipment, including held-for-sale, gross	165.9
Depreciation expense	12.4	13.6	$ 16.4
Land
Property, Plant and Equipment [Line Items]
Property and equipment	0.0	0.0
Work in process
Property, Plant and Equipment [Line Items]
Property and equipment	6.7	3.0
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 0.4	0.4
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment	$ 123.1	126.8
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	$ 22.6	22.7
Estimated useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 13.1	$ 13.9
Leasehold improvements | Headquarters
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Leasehold improvements | Maximum | Branches
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years