Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Nov. 30, 2023	Nov. 30, 2022	Nov. 30, 2023	Nov. 30, 2022	Feb. 28, 2023
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 5,704.5		$ 5,704.5		$ 7,393.1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,571.7		5,571.7		5,117.2
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,730.0		3,730.0		2,257.7
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,520.1		1,520.1		1,356.4
Financing Receivable, Originated Four Years before Latest Fiscal Year	763.2		763.2		520.7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	215.6		215.6		122.8
Financing Receivable, before Allowance for Credit Loss	$ 17,505.1		$ 17,505.1		$ 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	$ 148.7	$ 112.6	$ 401.7	$ 276.9
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff			120.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff			188.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff			36.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff			18.3
Financing Receivable, Originated, More than Five Years before Current Fiscal Year, Writeoff			11.4
Financing Receivable, Year One, Originated, Current Fiscal Year, Writeoff			26.1
Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	5,479.5		5,479.5		$ 7,121.1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,374.1		5,374.1		5,004.7
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,649.3		3,649.3		2,242.7
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,509.6		1,509.6		1,335.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	749.0		749.0		507.5
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	202.7		202.7		117.9
Financing Receivable, before Allowance for Credit Loss	$ 16,964.2		$ 16,964.2		$ 16,329.2
Total ending managed receivables as percentage by major credit grade	96.90%		96.90%		97.40%
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 125.1	96.3	$ 336.9	241.9
Other managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	23.6	$ 16.3	64.8	$ 35.0
Credit Grade A | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,217.4		3,217.4		$ 3,890.9
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,922.2		2,922.2		2,555.3
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,842.0		1,842.0		1,112.0
Financing Receivable, Originated Three Years before Latest Fiscal Year	725.5		725.5		677.1
Financing Receivable, Originated Four Years before Latest Fiscal Year	355.1		355.1		218.3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	69.4		69.4		36.3
Financing Receivable, before Allowance for Credit Loss	$ 9,131.6		$ 9,131.6		$ 8,489.9
Total ending managed receivables as percentage by major credit grade	52.20%		52.20%		50.60%
Credit Grade B | Core managed receivables
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 1,980.5		$ 1,980.5		$ 2,497.5
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,899.8		1,899.8		1,839.9
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,359.4		1,359.4		816.2
Financing Receivable, Originated Three Years before Latest Fiscal Year	564.5		564.5		488.9
Financing Receivable, Originated Four Years before Latest Fiscal Year	289.1		289.1		215.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	95.0		95.0		56.0
Financing Receivable, before Allowance for Credit Loss	$ 6,188.3		$ 6,188.3		$ 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	$ 281.6		$ 281.6		$ 732.7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	552.1		552.1		609.5
Financing Receivable, Originated Two Years before Latest Fiscal Year	447.9		447.9		314.5
Financing Receivable, Originated Three Years before Latest Fiscal Year	219.6		219.6		169.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	104.8		104.8		74.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	38.3		38.3		25.6
Financing Receivable, before Allowance for Credit Loss	$ 1,644.3		$ 1,644.3		$ 1,925.7
Total ending managed receivables as percentage by major credit grade	9.30%		9.30%		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	$ 225.0		$ 225.0		$ 272.0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	197.6		197.6		112.5
Financing Receivable, Originated Two Years before Latest Fiscal Year	80.7		80.7		15.0
Financing Receivable, Originated Three Years before Latest Fiscal Year	10.5		10.5		21.1
Financing Receivable, Originated Four Years before Latest Fiscal Year	14.2		14.2		13.2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	12.9		12.9		4.9
Financing Receivable, before Allowance for Credit Loss	$ 540.9		$ 540.9		$ 438.7
Total ending managed receivables as percentage by major credit grade	3.10%		3.10%		2.60%