Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2024	Nov. 30, 2023	Nov. 30, 2024	Nov. 30, 2023	Feb. 29, 2024
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 5,601.3		$ 5,601.3		$ 6,936.6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,218.5		5,218.5		5,074.3
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,689.9		3,689.9		3,333.9
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,244.5		2,244.5		1,308.8
Financing Receivable, Originated Four Years before Latest Fiscal Year	750.0		750.0		600.8
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	252.2		252.2		137.4
Financing Receivable, before Allowance for Credit Loss	$ 17,756.4		$ 17,756.4		$ 17,391.8
Total ending managed receivables as percentage by major credit grade	100.00%		100.00%		100.00%
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 150.2	$ 148.7	$ 447.1	$ 401.7	$ 561.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff			153.5		129.8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff			149.9		248.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff			85.3		41.0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff			24.3		19.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff			14.9		11.4
Financing Receivable, Year One, Originated, Current Fiscal Year, Writeoff			19.2		111.0
Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	5,352.8		5,352.8		6,637.6
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,023.8		5,023.8		4,898.0
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,560.2		3,560.2		3,261.3
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,192.5		2,192.5		1,299.5
Financing Receivable, Originated Four Years before Latest Fiscal Year	743.7		743.7		588.7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	243.5		243.5		128.2
Financing Receivable, before Allowance for Credit Loss	$ 17,116.5		$ 17,116.5		$ 16,813.3
Total ending managed receivables as percentage by major credit grade	96.40%		96.40%		96.70%
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 129.0	125.1	$ 373.1	336.9
Other managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	21.2	$ 23.6	74.0	$ 64.8
Credit Grade A | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,339.0		3,339.0		$ 3,922.7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,902.1		2,902.1		2,660.6
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,903.4		1,903.4		1,635.1
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,061.0		1,061.0		614.0
Financing Receivable, Originated Four Years before Latest Fiscal Year	324.1		324.1		268.7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	86.1		86.1		40.0
Financing Receivable, before Allowance for Credit Loss	$ 9,615.7		$ 9,615.7		$ 9,141.1
Total ending managed receivables as percentage by major credit grade	54.20%		54.20%		52.60%
Credit Grade B | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 1,670.2		$ 1,670.2		$ 2,370.8
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,819.6		1,819.6		1,738.8
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,293.7		1,293.7		1,225.9
Financing Receivable, Originated Three Years before Latest Fiscal Year	854.0		854.0		493.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	300.0		300.0		233.4
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	107.9		107.9		61.3
Financing Receivable, before Allowance for Credit Loss	$ 6,045.4		$ 6,045.4		$ 6,123.5
Total ending managed receivables as percentage by major credit grade	34.00%		34.00%		35.20%
Credit Grade C And Other | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 343.6		$ 343.6		$ 344.1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	302.1		302.1		498.6
Financing Receivable, Originated Two Years before Latest Fiscal Year	363.1		363.1		400.3
Financing Receivable, Originated Three Years before Latest Fiscal Year	277.5		277.5		192.2
Financing Receivable, Originated Four Years before Latest Fiscal Year	119.6		119.6		86.6
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	49.5		49.5		26.9
Financing Receivable, before Allowance for Credit Loss	$ 1,455.4		$ 1,455.4		$ 1,548.7
Total ending managed receivables as percentage by major credit grade	8.20%		8.20%		8.90%
Credit Grade C And Other | Other managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 248.5		$ 248.5		$ 299.0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	194.7		194.7		176.3
Financing Receivable, Originated Two Years before Latest Fiscal Year	129.7		129.7		72.6
Financing Receivable, Originated Three Years before Latest Fiscal Year	52.0		52.0		9.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	6.3		6.3		12.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	8.7		8.7		9.2
Financing Receivable, before Allowance for Credit Loss	$ 639.9		$ 639.9		$ 578.5
Total ending managed receivables as percentage by major credit grade	3.60%		3.60%		3.30%