Loans Receivable (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Document Period End Date			Dec. 31, 2019
Transfers	[1]		$ 0.0	$ 0.0	$ 0.0
Transfers	[2]		$ 0.0	0.0	0.0
Age of Consumer Loans contractual payments due with no forecasted future net cash flows			120 months
Impact of Forecast Change on Credit Losses		$ 41.6
Impact of Forecast Change on Finance Charges		7.3
Impact of Forecast Change on Net Income		$ 30.8
Impact of Forecast Change on Loan Portfolio Yield		9000.00%
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers	[1]	$ (89.0)	$ (87.2)	(78.2)	(93.1)
Transfers	[2]	$ (31.8)	(13.1)	(13.7)	(31.8)
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers	[1]		87.2	78.2	93.1
Transfers	[2]		$ 13.1	$ 13.7	$ 31.8

[1] Under our Portfolio Program, certain events may result in Dealers forfeiting their rights to Dealer Holdback.  We transfer the Dealer’s outstanding Dealer Loan balance and the related allowance for credit losses balance to Purchased Loans in the period this forfeiture occurs.

[2] Under our Portfolio Program, certain events may result in Dealers forfeiting their rights to Dealer Holdback.  We transfer the Dealer’s outstanding Dealer Loan balance and the related allowance for credit losses balance to Purchased Loans in the period this forfeiture occurs.