Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	Feb. 29, 2020	Feb. 28, 2019
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 13,617.8	$ 12,510.2
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]
Total ending managed receivables	$ 6,915.9	$ 6,225.6
Total ending managed receivables as percentage by major credit grade	50.80%	49.80%
Credit Grade B
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 4,841.2	$ 4,488.2
Total ending managed receivables as percentage by major credit grade	35.60%	35.90%
Credit Grade C And Other
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 1,860.7	$ 1,796.4
Total ending managed receivables as percentage by major credit grade	13.60%	14.30%