Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	May 31, 2020	Feb. 29, 2020
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 957.4
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,527.1
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,342.8
Financing Receivable, Originated Three Years before Latest Fiscal Year	1,960.7
Financing Receivable, Originated Four Years before Latest Fiscal Year	991.3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	392.6
Total ending managed receivables	$ 13,171.9	$ 13,617.8
Total ending managed receivables as percentage by major credit grade	100.00%	100.00%
Credit Grade A
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 493.7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,928.5
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,689.5
Financing Receivable, Originated Three Years before Latest Fiscal Year	957.6
Financing Receivable, Originated Four Years before Latest Fiscal Year	450.1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	139.7
Total ending managed receivables	$ 6,659.1	$ 6,915.9
Total ending managed receivables as percentage by major credit grade	50.60%	50.80%
Credit Grade B
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 334.0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,891.8
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,214.7
Financing Receivable, Originated Three Years before Latest Fiscal Year	731.3
Financing Receivable, Originated Four Years before Latest Fiscal Year	367.2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	160.9
Total ending managed receivables	$ 4,699.9	$ 4,841.2
Total ending managed receivables as percentage by major credit grade	35.70%	35.60%
Credit Grade C And Other
Financing Receivable, By Major Credit Grade [Line Items]
Financing Receivable, Originated in Current Fiscal Year	$ 129.7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	706.8
Financing Receivable, Originated Two Years before Latest Fiscal Year	438.6
Financing Receivable, Originated Three Years before Latest Fiscal Year	271.8
Financing Receivable, Originated Four Years before Latest Fiscal Year	174.0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	92.0
Total ending managed receivables	$ 1,812.9	$ 1,860.7
Total ending managed receivables as percentage by major credit grade	13.70%	13.60%