Auto Loan Receivables (Allowance for Loan Losses) (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
Aug. 31, 2024	Aug. 31, 2023	Aug. 31, 2024	Aug. 31, 2023	Feb. 29, 2024	May 31, 2024	May 31, 2023	Feb. 28, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 500,834,000	$ 538,000,000.0	$ 500,834,000	$ 538,000,000.0	$ 482,790,000	$ 493,100,000	$ 535,400,000	$ 507,200,000
Financing Receivable, Allowance for Credit Loss, Writeoff	(163,800,000)	(143,200,000)	(296,900,000)	(253,000,000.0)	$ (561,500,000)
Financing Receivable, Allowance for Credit Loss, Recovery	58,900,000	56,000,000.0	121,100,000	113,100,000
Provision for Loan, Lease, and Other Losses	$ 112,600,000	$ 89,800,000	193,800,000	$ 170,700,000
Item As Percent Of Total Ending Managed Receivables, Period Increase (Decrease)			$ 4
Allowance For Loan Losses, percent
Financing Receivable, Allowance for Credit Loss [Line Items]
Item as percent of total ending managed receivables	2.82%	3.08%	2.82%	3.08%	2.78%	2.79%	3.11%	3.02%
Core managed receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 417,300,000	$ 433,000,000.0	$ 417,300,000	$ 433,000,000.0	$ 389,700,000	$ 396,600,000	$ 427,500,000	$ 401,500,000
Financing Receivable, Allowance for Credit Loss, Writeoff	(131,100,000)	(118,700,000)	(244,100,000)	(211,800,000)
Financing Receivable, Allowance for Credit Loss, Recovery	52,100,000	48,500,000	106,000,000.0	99,000,000.0
Provision for Loan, Lease, and Other Losses	99,700,000	75,700,000	165,700,000	144,300,000
Other managed receivables
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	83,500,000	105,000,000.0	83,500,000	105,000,000.0	$ 93,100,000	$ 96,500,000	$ 107,900,000	$ 105,700,000
Financing Receivable, Allowance for Credit Loss, Writeoff	(32,700,000)	(24,500,000)	(52,800,000)	(41,200,000)
Financing Receivable, Allowance for Credit Loss, Recovery	6,800,000	7,500,000	15,100,000	14,100,000
Provision for Loan, Lease, and Other Losses	$ 12,900,000	$ 14,100,000	$ 28,100,000	$ 26,400,000

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- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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