Loans Receivable (Summary of Provision for Credit Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	$ 8.4	$ 556.9	$ 76.4
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	(28.2)	239.7	65.9
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	36.6	317.2	10.5
New Consumer Loan assignments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	365.1	518.6	0.0
New Consumer Loan assignments | Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	153.1	209.7	0.0
New Consumer Loan assignments | Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	212.0	308.9	$ 0.0
Forecast Changes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	(356.7)	38.3
Forecast Changes [Member] | Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	(181.3)	30.0
Forecast Changes [Member] | Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	$ (175.4)	$ 8.3