Financing Receivables - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Net unamortized discount on financing receivable	$ 18.4	$ 19.3
Adjustment for new accounting standards	(191.7)	(1,816.1)	$ (1,792.9)	$ (1,738.8)
Financing receivable, allowance for credit loss	66.8	41.3	43.8
Financing receivable, allowance for credit loss, current	22.4	17.2
Financing receivable, allowance for credit losses	$ 44.4	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	$ 54.3	29.4	29.6
Financing receivable, allowance for credit loss, current	15.8	10.0
Financing receivable, allowance for credit losses	$ 38.5	19.4
PSAs | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, payment terms	5 years
Franchisee Notes
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, period for uncollectible status	1 year
Financing receivable, allowance for credit loss	$ 12.5	11.9	14.2
Financing receivable, allowance for credit loss, current	6.6	7.2
Financing receivable, allowance for credit losses	$ 5.9	4.7
Franchisee Notes | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, payment terms	10 years
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for trade accounts and financing receivables		22.1
Adjustment for new accounting standards		16.9
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