Summary of Significant Accounting Policies (Property, Fixtures and Equipment) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Capitalized internal costs for construction in progress		$ 6.4	$ 6.9	$ 9.1
Capitalized computer equipment and software, additions		7.4	13.5
Property, fixtures and equipment, net [Member]
Property, Plant and Equipment [Line Items]
Capitalized computer equipment and software, net		$ 25.7	$ 33.2
Buildings [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	[1]	5 years
Buildings [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	[1]	30 years
Furniture and fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		5 years
Furniture and fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		7 years
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		2 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		7 years
Computer equipment and software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		3 years
Computer equipment and software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life		7 years

[1] Includes improvements to leased properties which are depreciated over the shorter of their useful life or the reasonably certain lease term, including renewal periods that are reasonably certain.