Loans Receivable (Summary Of Changes In Allowance For Credit Losses) (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]
Balance, beginning of period			$ 461.9	$ 429.4	$ 320.4
Provision for credit losses			76.4	56.9	129.3
Transfers	[1]		0.0	0.0	0.0
Write-offs			(4.9)	(28.6)	(22.1)
Recoveries	[2],[3]		2.6	4.2	1.8
Balance, end of period		$ 429.4	536.0	461.9	429.4
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period			378.1	366.0	309.3
Provision for credit losses			65.9	48.0	103.4
Transfers	[1]	(31.8)	(13.1)	(13.7)	(31.8)
Write-offs			(4.4)	(25.2)	(16.4)
Recoveries	[2],[3]		1.5	3.0	1.5
Balance, end of period		366.0	428.0	378.1	366.0
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period			83.8	63.4	11.1
Provision for credit losses			10.5	8.9	25.9
Transfers	[1]		13.1	13.7	31.8
Write-offs			(0.5)	(3.4)	(5.7)
Recoveries	[2],[3]		1.1	1.2	0.3
Balance, end of period		$ 63.4	$ 108.0	$ 83.8	$ 63.4

[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] Represents collections received on previously written off Loans.

[3] Represents collections received on previously written off Loans.