Auto Loan Receivables (Past Due Receivables) (Details) - USD ($) $ in Millions	May 31, 2023	Feb. 28, 2023
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	$ 16,304.7	$ 15,930.4
Past due receivables as a percentage of total ending managed receivables	5.15%	5.00%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 885.9	$ 837.5
Financing Receivable, before Allowance for Credit Loss	$ 17,190.6	$ 16,767.9
Item As A Percent Of Total Ending Managed Receivables	100.00%	100.00%
One to Thirty Days Past Due
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	94.85%	95.00%
Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	2.93%	2.90%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 503.4	$ 486.8
Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	1.81%	1.71%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 310.4	$ 287.2
Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	0.41%	0.39%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 72.1	$ 63.5
Core managed receivables
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	15,982.3	15,602.8
Financing Receivable, before Allowance for Credit Loss, Noncurrent	759.2	726.4
Financing Receivable, before Allowance for Credit Loss	16,741.5	16,329.2
Core managed receivables | Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	439.9	426.2
Core managed receivables | Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	258.9	245.1
Core managed receivables | Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	60.4	55.1
Core managed receivables | Credit Grade A
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	8,745.3	8,450.3
Financing Receivable, before Allowance for Credit Loss, Noncurrent	42.9	39.6
Financing Receivable, before Allowance for Credit Loss	8,788.2	8,489.9
Core managed receivables | Credit Grade A | Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	27.4	25.1
Core managed receivables | Credit Grade A | Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	11.7	10.6
Core managed receivables | Credit Grade A | Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	3.8	3.9
Core managed receivables | Credit Grade B
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	5,691.1	5,540.2
Financing Receivable, before Allowance for Credit Loss, Noncurrent	385.5	373.4
Financing Receivable, before Allowance for Credit Loss	6,076.6	5,913.6
Core managed receivables | Credit Grade B | Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	229.4	225.7
Core managed receivables | Credit Grade B | Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	126.1	120.0
Core managed receivables | Credit Grade B | Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	30.0	27.7
Core managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	1,545.9	1,612.3
Financing Receivable, before Allowance for Credit Loss, Noncurrent	330.8	313.4
Financing Receivable, before Allowance for Credit Loss	1,876.7	1,925.7
Core managed receivables | Credit Grade C And Other | Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	183.1	175.4
Core managed receivables | Credit Grade C And Other | Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	121.1	114.5
Core managed receivables | Credit Grade C And Other | Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	26.6	23.5
Other managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Current	322.4	327.6
Financing Receivable, before Allowance for Credit Loss, Noncurrent	126.7	111.1
Financing Receivable, before Allowance for Credit Loss	449.1	438.7
Other managed receivables | Credit Grade C And Other | Thirty One To Sixty Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	63.5	60.6
Other managed receivables | Credit Grade C And Other | Sixty One To Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	51.5	42.1
Other managed receivables | Credit Grade C And Other | Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 11.7	$ 8.4