Financing Receivables - Narrative (Details) - USD ($) $ in Millions	Jan. 01, 2020	Sep. 25, 2020	Jun. 26, 2020	Mar. 27, 2020	Dec. 31, 2019	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Net unamortized discount on financing receivable		$ 18.6			$ 19.3
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Adjustment for new accounting standards		(1,587.4)			(1,816.1)
Financing receivable, allowance for credit loss		58.1			41.3				$ 43.8
Financing receivable, allowance for credit loss, current		22.1			17.2
Financing receivable, allowance for credit losses		$ 36.0			24.1
PSAs
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, period for uncollectible status		180 days
Financing receivable, allowance for credit loss		$ 45.4			29.4				29.6
Financing receivable, allowance for credit loss, current		15.0			10.0
Financing receivable, allowance for credit losses		$ 30.4			19.4
Franchisee Notes
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, period for uncollectible status		1 year
Financing receivable, allowance for credit loss		$ 12.7			11.9				14.2
Financing receivable, allowance for credit loss, current		7.1			7.2
Financing receivable, allowance for credit losses		5.6			4.7
Net Parent Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Adjustment for new accounting standards		$ (1,445.8)	$ (1,535.4)	$ (1,630.9)	(1,662.5)	$ (1,554.7)	$ (1,701.4)	$ (1,695.6)	(1,663.5)
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for trade accounts and financing receivables	$ 22.1
Financing receivable, allowance for credit loss					18.5				0.0
Cumulative Effect, Period of Adoption, Adjustment | PSAs
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss					17.5				0.0
Cumulative Effect, Period of Adoption, Adjustment | Franchisee Notes
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss					1.0				$ 0.0
Cumulative Effect, Period of Adoption, Adjustment | Net Parent Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Adjustment for new accounting standards	$ 16.9				$ 16.9