Auto Loan Receivables (Auto Loan Receivables, Net) (Details) (USD $)	Aug. 31, 2012		May 31, 2012	Feb. 29, 2012		Aug. 31, 2011		May 31, 2011	Feb. 28, 2011
Non-recourse notes payable	$ 5,080,000,000			$ 4,680,000,000
Total ending managed receivables	5,342,100,000	[1]		4,981,800,000	[1]	4,707,700,000	[1]		4,334,600,000	[1]
Accrued interest and fees	25,700,000			23,100,000		24,700,000			20,900,000
Other	(3,100,000)			(1,800,000)		2,900,000			4,000,000
Less allowance for loan losses	(49,500,000)		(46,600,000)	(43,300,000)		(36,200,000)		(34,300,000)	(38,900,000)
Auto loan receivables, net	5,315,232,000			4,959,847,000		4,699,100,000			4,320,600,000
Warehouse Facilities Receivables [Member]
Total ending managed receivables	1,066,000,000			553,000,000		1,559,000,000			943,000,000
Term securitizations [Member]
Total ending managed receivables	4,029,700,000			4,211,800,000		2,865,000,000			3,193,100,000
Other receivables [Member]
Total ending managed receivables	$ 246,400,000	[2]		$ 217,000,000	[2]	$ 283,700,000	[2]		$ 198,500,000	[2]

[1] Classified based on credit grade assigned when customers were initially approved for financing.

[2] Other receivables includes receivables not funded through the warehouse facilities or term securitizations