Loans Receivable (Summary Of Changes In Allowance For Credit Losses) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period		$ 243.6	$ 206.9	$ 195.4
Provision for credit losses		90.2	41.5	12.8
Write-offs		(14.8)	(6.6)	(3.2)
Recoveries	[1],[2]	1.4	1.8	1.9
Balance, end of period		320.4	243.6	206.9
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period		235.1	198.1	185.7
Provision for credit losses		87.3	41.8	13.7
Write-offs		(14.4)	(6.4)	(3.1)
Recoveries	[1],[2]	1.3	1.6	1.8
Balance, end of period		309.3	235.1	198.1
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period		8.5	8.8	9.7
Provision for credit losses		2.9	(0.3)	(0.9)
Write-offs		(0.4)	(0.2)	(0.1)
Recoveries	[1],[2]	0.1	0.2	0.1
Balance, end of period		$ 11.1	$ 8.5	$ 8.8

[1] Represents collections received on previously written off Loans

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