Loans Receivable (Summary Of Information Related To New Consumer Loan Assignments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractual net cash flows at the time of assignment		$ 6,658.1	$ 6,763.9	$ 6,438.1
New Consumer Loan Assignments		5,131.6	5,305.0	5,074.4
Fair value at the time of assignment		3,641.2	3,772.2	3,595.8
Provision for credit losses		(556.9)	(76.4)	(56.9)
Expected future finance charges at the time of assignment	[1]	2,009.0	1,532.8	1,478.6
Expected net Loan income at the time of assignment	[2]	1,490.4	1,532.8	1,478.6
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractual net cash flows at the time of assignment		3,506.9	3,810.6	3,827.4
New Consumer Loan Assignments		3,113.4	3,396.1	3,405.0
Fair value at the time of assignment		2,207.8	2,424.5	2,414.8
Provision for credit losses		(239.7)	(65.9)	(48.0)
Expected future finance charges at the time of assignment	[1]	1,115.3	971.6	990.2
Expected net Loan income at the time of assignment	[2]	905.6	971.6	990.2
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractual net cash flows at the time of assignment		3,151.2	2,953.3	2,610.7
New Consumer Loan Assignments		2,018.2	1,908.9	1,669.4
Fair value at the time of assignment		1,433.4	1,347.7	1,181.0
Provision for credit losses		(317.2)	(10.5)	(8.9)
Expected future finance charges at the time of assignment	[1]	893.7	561.2	488.4
Expected net Loan income at the time of assignment	[2]	584.8	561.2	488.4
New Consumer Loan assignments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses		(518.6)	0.0	0.0
New Consumer Loan assignments | Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses		(209.7)	0.0	0.0
New Consumer Loan assignments | Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses		$ (308.9)	$ 0.0	$ 0.0

[1] Represents revenue that is expected to be recognized on a level-yield basis over the lives of the Loans.

[2] Represents the amount that expected net cash flows at the time of assignment (2) exceed Loans receivable at the time of assignment (3).