Auto Loan Receivables (Ending Managed Receivables By Major Credit Grade) (Details) - USD ($) $ in Millions	Feb. 28, 2021	Feb. 29, 2020
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 13,847.2	$ 13,617.8
Total ending managed receivables as percentage by major credit grade	100.00%	100.00%
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 5,561.7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,112.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,337.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,226.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	494.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	113.9
Credit Grade A [Member]
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 6,874.1	$ 6,915.9
Total ending managed receivables as percentage by major credit grade	49.60%	50.80%
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,782.0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,146.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,146.7
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	568.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	199.6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	30.4
Credit Grade B
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 5,008.9	$ 4,841.2
Total ending managed receivables as percentage by major credit grade	36.20%	35.60%
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,993.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,424.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	870.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	476.0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	195.5
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	49.2
Credit Grade C And Other
Financing Receivable, By Major Credit Grade [Line Items]
Total ending managed receivables	$ 1,964.2	$ 1,860.7
Total ending managed receivables as percentage by major credit grade	14.20%	13.60%
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 786.1
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	541.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	320.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	182.0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	99.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	$ 34.3