Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	Nov. 30, 2019	Feb. 28, 2019
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 13,352.6	$ 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	$ 6,691.4	$ 6,225.6
Total ending managed receivables as percentage by major credit grade	50.10%	49.80%
Credit Grade B
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 4,813.9	$ 4,488.2
Total ending managed receivables as percentage by major credit grade	36.10%	35.90%
Credit Grade C And Other
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 1,847.3	$ 1,796.4
Total ending managed receivables as percentage by major credit grade	13.80%	14.30%