Loans Receivable Loans Receivable (Summary of Past-Due Status) (Details) - USD ($) $ in Millions		Jun. 30, 2024		Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	$ 10,884.2		$ 10,020.1
Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	7,539.1		6,507.1
Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	1,655.2		1,694.5
Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	1,423.3		1,568.8
Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	266.6		249.7
Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	7,980.6		7,065.5
Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	5,681.7	[4]	4,742.3
Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	1,208.6		1,181.3
Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	936.0		998.0
Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	154.3		143.9
Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	2,903.6		2,954.6
Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	1,857.4		1,764.8
Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	446.6		513.2
Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	487.3		570.8
Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	112.3		105.8
Loans Originating Five Years Prior And Before
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	560.8		319.4
Loans Originating Five Years Prior And Before | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	79.4		24.2
Loans Originating Five Years Prior And Before | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	47.8		16.8
Loans Originating Five Years Prior And Before | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	183.9		73.5
Loans Originating Five Years Prior And Before | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	249.7		204.9
Loans Originating Five Years Prior And Before | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	285.2		172.4
Loans Originating Five Years Prior And Before | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	36.1	[4]	11.7
Loans Originating Five Years Prior And Before | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	21.3		7.9
Loans Originating Five Years Prior And Before | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	86.0		35.0
Loans Originating Five Years Prior And Before | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	141.8		117.8
Loans Originating Five Years Prior And Before | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	275.6		147.0
Loans Originating Five Years Prior And Before | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	43.3		12.5
Loans Originating Five Years Prior And Before | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	26.5		8.9
Loans Originating Five Years Prior And Before | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	97.9		38.5
Loans Originating Five Years Prior And Before | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	107.9		87.1
Loans Originating Four Years Prior
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	569.9		511.6
Loans Originating Four Years Prior | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	210.4		150.7
Loans Originating Four Years Prior | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	105.0		83.8
Loans Originating Four Years Prior | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	239.6		237.6
Loans Originating Four Years Prior | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	14.9		39.5
Loans Originating Four Years Prior | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	343.8		241.1
Loans Originating Four Years Prior | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	127.0	[4]	69.9
Loans Originating Four Years Prior | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	62.0		38.0
Loans Originating Four Years Prior | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	144.0		111.2
Loans Originating Four Years Prior | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	10.8		22.0
Loans Originating Four Years Prior | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	226.1		270.5
Loans Originating Four Years Prior | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	83.4		80.8
Loans Originating Four Years Prior | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	43.0		45.8
Loans Originating Four Years Prior | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	95.6		126.4
Loans Originating Four Years Prior | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	4.1		17.5
Loans Originating Three Years Prior
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	913.9		813.5
Loans Originating Three Years Prior | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	426.6		328.9
Loans Originating Three Years Prior | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	178.0		165.5
Loans Originating Three Years Prior | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	307.5		314.5
Loans Originating Three Years Prior | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	1.8		4.6
Loans Originating Three Years Prior | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	610.0		493.6
Loans Originating Three Years Prior | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	288.2	[4]	201.7
Loans Originating Three Years Prior | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	117.1		98.0
Loans Originating Three Years Prior | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	203.2		190.4
Loans Originating Three Years Prior | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	1.5		3.5
Loans Originating Three Years Prior | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	303.9		319.9
Loans Originating Three Years Prior | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	138.4		127.2
Loans Originating Three Years Prior | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	60.9		67.5
Loans Originating Three Years Prior | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	104.3		124.1
Loans Originating Three Years Prior | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	0.3		1.1
Loans Originating Two Years Prior
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	1,877.4		1,228.1
Loans Originating Two Years Prior | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	1,128.4		596.6
Loans Originating Two Years Prior | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	355.5		262.1
Loans Originating Two Years Prior | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	393.3		368.7
Loans Originating Two Years Prior | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	0.2		0.7
Loans Originating Two Years Prior | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	1,345.2		826.3
Loans Originating Two Years Prior | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	813.8	[4]	407.3
Loans Originating Two Years Prior | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	251.8		173.4
Loans Originating Two Years Prior | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	279.4		245.0
Loans Originating Two Years Prior | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	0.2		0.6
Loans Originating Two Years Prior | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	532.2		401.8
Loans Originating Two Years Prior | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	314.6		189.3
Loans Originating Two Years Prior | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	103.7		88.7
Loans Originating Two Years Prior | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	113.9		123.7
Loans Originating Two Years Prior | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	0.0		0.1
Loans Originating In The Prior Year
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	3,712.5		2,440.3
Loans Originating In The Prior Year | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	2,777.4		1,518.0
Loans Originating In The Prior Year | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	647.1		499.8
Loans Originating In The Prior Year | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	288.0		422.5
Loans Originating In The Prior Year | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	0.0		0.0
Loans Originating In The Prior Year | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	2,766.6		1,773.3
Loans Originating In The Prior Year | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	2,063.5	[4]	1,109.4
Loans Originating In The Prior Year | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	489.1		360.4
Loans Originating In The Prior Year | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	214.0		303.5
Loans Originating In The Prior Year | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	0.0		0.0
Loans Originating In The Prior Year | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	945.9		667.0
Loans Originating In The Prior Year | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	713.9		408.6
Loans Originating In The Prior Year | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	158.0		139.4
Loans Originating In The Prior Year | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	74.0		119.0
Loans Originating In The Prior Year | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	0.0		0.0
Loans Originating In The Current Year
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2]	3,249.7		4,707.2
Loans Originating In The Current Year | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3],[4]	2,916.9		3,888.7
Loans Originating In The Current Year | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	321.8		666.5
Loans Originating In The Current Year | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[3]	11.0		152.0
Loans Originating In The Current Year | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[2],[5]	0.0		0.0
Loans Originating In The Current Year | Dealer Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1]	2,629.8		3,558.8
Loans Originating In The Current Year | Dealer Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	2,353.1	[4]	2,942.3
Loans Originating In The Current Year | Dealer Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	267.3		503.6
Loans Originating In The Current Year | Dealer Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[3]	9.4		112.9
Loans Originating In The Current Year | Dealer Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[1],[5]	0.0		0.0
Loans Originating In The Current Year | Purchased Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2]	619.9		1,148.4
Loans Originating In The Current Year | Purchased Loans [Member] | Current, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3],[4]	563.8		946.4
Loans Originating In The Current Year | Purchased Loans [Member] | Past Due 11-90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	54.5		162.9
Loans Originating In The Current Year | Purchased Loans [Member] | Past Due Over 90 Days, Pre-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[3]	1.6		39.1
Loans Originating In The Current Year | Purchased Loans [Member] | Post-term [Member]
Financing Receivable, Past Due [Line Items]
Loans receivable	[2],[5]	$ 0.0		$ 0.0

[1] As Consumer Loans are aggregated by Dealer for purposes of recognizing revenue and measuring credit losses, the Dealer Loan amount was estimated by allocating the balance of each Dealer Loan to the underlying Consumer Loans based on the forecasted future collections of each Consumer Loan.

[2] As certain Consumer Loans are aggregated by Dealer or month of purchase for purposes of recognizing revenue and measuring credit losses, the Purchased Loan amount was estimated by allocating the balance of certain Purchased Loans to the underlying Consumer Loans based on the forecasted future collections of each Consumer Loan.

[3] Represents the Loan balance attributable to Consumer Loans outstanding within their initial loan terms.

[4] We consider a Consumer Loan to be current for purposes of forecasting expected collection rates if contractual repayments are less than 11 days past due.

[5] Represents the Loan balance attributable to Consumer Loans outstanding beyond their initial loan terms.