Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2023	Aug. 31, 2022	Feb. 28, 2023
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 4,186.5		$ 4,186.5		$ 7,393.1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	6,108.6		6,108.6		5,117.2
Financing Receivable, Originated Two Years before Latest Fiscal Year	4,146.4		4,146.4		2,257.7
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,741.7		1,741.7		1,356.4
Financing Receivable, Originated Four Years before Latest Fiscal Year	938.8		938.8		520.7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	320.8		320.8		122.8
Financing Receivable, before Allowance for Credit Loss	$ 17,442.8		$ 17,442.8		$ 16,767.9
Total ending managed receivables as percentage by major credit grade	100.00%		100.00%		100.00%
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 143.2	$ 96.1	$ 253.0	$ 164.3
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff			82.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff			120.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff			24.7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff			12.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff			8.2
Financing Receivable, Year One, Originated, Current Fiscal Year, Writeoff			4.9
Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	4,047.1		4,047.1		$ 7,121.1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,886.7		5,886.7		5,004.7
Financing Receivable, Originated Two Years before Latest Fiscal Year	4,056.6		4,056.6		2,242.7
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,729.7		1,729.7		1,335.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	922.7		922.7		507.5
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	303.9		303.9		117.9
Financing Receivable, before Allowance for Credit Loss	$ 16,946.7		$ 16,946.7		$ 16,329.2
Total ending managed receivables as percentage by major credit grade	97.20%		97.20%		97.40%
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 118.7	84.2	$ 211.8	145.6
Other managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	24.5	$ 11.9	41.2	$ 18.7
Credit Grade A | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2,349.6		2,349.6		$ 3,890.9
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	3,202.6		3,202.6		2,555.3
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,058.3		2,058.3		1,112.0
Financing Receivable, Originated Three Years before Latest Fiscal Year	841.9		841.9		677.1
Financing Receivable, Originated Four Years before Latest Fiscal Year	450.0		450.0		218.3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	112.2		112.2		36.3
Financing Receivable, before Allowance for Credit Loss	$ 9,014.6		$ 9,014.6		$ 8,489.9
Total ending managed receivables as percentage by major credit grade	51.70%		51.70%		50.60%
Credit Grade B | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 1,473.2		$ 1,473.2		$ 2,497.5
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,074.3		2,074.3		1,839.9
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,502.1		1,502.1		816.2
Financing Receivable, Originated Three Years before Latest Fiscal Year	639.8		639.8		488.9
Financing Receivable, Originated Four Years before Latest Fiscal Year	348.7		348.7		215.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	137.8		137.8		56.0
Financing Receivable, before Allowance for Credit Loss	$ 6,175.9		$ 6,175.9		$ 5,913.6
Total ending managed receivables as percentage by major credit grade	35.40%		35.40%		35.30%
Credit Grade C And Other | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 224.3		$ 224.3		$ 732.7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	609.8		609.8		609.5
Financing Receivable, Originated Two Years before Latest Fiscal Year	496.2		496.2		314.5
Financing Receivable, Originated Three Years before Latest Fiscal Year	248.0		248.0		169.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	124.0		124.0		74.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	53.9		53.9		25.6
Financing Receivable, before Allowance for Credit Loss	$ 1,756.2		$ 1,756.2		$ 1,925.7
Total ending managed receivables as percentage by major credit grade	10.10%		10.10%		11.50%
Credit Grade C And Other | Other managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 139.4		$ 139.4		$ 272.0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	221.9		221.9		112.5
Financing Receivable, Originated Two Years before Latest Fiscal Year	89.8		89.8		15.0
Financing Receivable, Originated Three Years before Latest Fiscal Year	12.0		12.0		21.1
Financing Receivable, Originated Four Years before Latest Fiscal Year	16.1		16.1		13.2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	16.9		16.9		4.9
Financing Receivable, before Allowance for Credit Loss	$ 496.1		$ 496.1		$ 438.7
Total ending managed receivables as percentage by major credit grade	2.80%		2.80%		2.60%