Auto Loan Receivables (Past Due Receivables) (Details) - USD ($) $ in Millions	Feb. 28, 2022	Feb. 28, 2021
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	$ 15,652.3	$ 13,847.2
Past due receivables as a percentage of total ending managed receivables	4.02%	2.83%
Financing Receivable, before Allowance for Credit Loss, Current	$ 15,022.3	$ 13,454.7
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 630.0	$ 392.5
Managed Receivables
Financing Receivable, Past Due [Line Items]
Item as percent of total ending managed receivables	100.00%	100.00%
Core managed receivables
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	$ 15,390.0	$ 13,682.7
Financing Receivable, before Allowance for Credit Loss, Current	14,815.9	13,328.6
Financing Receivable, before Allowance for Credit Loss, Noncurrent	574.1	354.1
Core managed receivables | Credit Grade A [Member]
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	7,749.7	6,874.1
Financing Receivable, before Allowance for Credit Loss, Current	7,711.9	6,847.2
Financing Receivable, before Allowance for Credit Loss, Noncurrent	37.8	26.9
Core managed receivables | Credit Grade B
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	5,670.1	5,008.9
Financing Receivable, before Allowance for Credit Loss, Current	5,401.3	4,840.3
Financing Receivable, before Allowance for Credit Loss, Noncurrent	268.8	168.6
Core managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	1,970.2	1,799.7
Financing Receivable, before Allowance for Credit Loss, Current	1,702.7	1,641.1
Financing Receivable, before Allowance for Credit Loss, Noncurrent	267.5	158.6
Other managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Total ending managed receivables	262.3	164.5
Financing Receivable, before Allowance for Credit Loss, Current	206.4	126.1
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 55.9	$ 38.4
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	2.50%	1.78%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 392.1	$ 246.2
Thirty One To Sixty Days Past Due [Member] | Core managed receivables
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	359.1	224.2
Thirty One To Sixty Days Past Due [Member] | Core managed receivables | Credit Grade A [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	25.4	17.3
Thirty One To Sixty Days Past Due [Member] | Core managed receivables | Credit Grade B
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	173.3	108.9
Thirty One To Sixty Days Past Due [Member] | Core managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	160.4	98.0
Thirty One To Sixty Days Past Due [Member] | Other managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 33.0	$ 22.0
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	1.21%	0.86%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 189.1	$ 119.9
Sixty One To Ninety Days Past Due [Member] | Core managed receivables
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	170.0	105.9
Sixty One To Ninety Days Past Due [Member] | Core managed receivables | Credit Grade A [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	9.2	7.0
Sixty One To Ninety Days Past Due [Member] | Core managed receivables | Credit Grade B
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	75.6	48.4
Sixty One To Ninety Days Past Due [Member] | Core managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	85.2	50.5
Sixty One To Ninety Days Past Due [Member] | Other managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 19.1	$ 14.0
Greater Than Ninety Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	0.31%	0.19%
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 48.8	$ 26.4
Greater Than Ninety Days Past Due [Member] | Core managed receivables
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	45.0	24.0
Greater Than Ninety Days Past Due [Member] | Core managed receivables | Credit Grade A [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	3.2	2.6
Greater Than Ninety Days Past Due [Member] | Core managed receivables | Credit Grade B
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	19.9	11.3
Greater Than Ninety Days Past Due [Member] | Core managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	21.9	10.1
Greater Than Ninety Days Past Due [Member] | Other managed receivables | Credit Grade C And Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 3.8	$ 2.4
Financial Asset, 1 to 29 Days Past Due
Financing Receivable, Past Due [Line Items]
Past due receivables as a percentage of total ending managed receivables	95.98%	97.17%