Loans Receivable (Summary of Changes In Allowance for Credit Losses) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Write-offs		$ 0.0	$ 0.0	$ 0.0	$ 0.0
Recoveries	[1]	0.0	0.0	0.0	0.0
Balance, end of period		3,310.9		3,310.9
Dealer Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Write-offs		0.0	0.0	0.0	0.0
Recoveries	[1]	0.0	0.0	0.0	0.0
Balance, end of period		1,634.8		1,634.8
Purchased Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Write-offs		0.0	0.0	0.0	0.0
Recoveries	[1]	0.0	$ 0.0	0.0	$ 0.0
Balance, end of period		$ 1,676.1		$ 1,676.1

[1] The Dealer Loans amount represents net cash flows received (collection less any related Dealer Holdback payments) on Dealer Loans that were previously written off in full. The Purchased Loans amount represents collections received on Purchased Loans that were previously written off in full.