Fair Value Measurements Fair Value, Measured on Recurring Basis Level 3 (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Securitized Beneficial Interests [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	$ 25,864
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other income	1,373	288
Fair Value, Measurements, Recurring [Member] | Securitized Beneficial Interests [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	15,797	25,125
Issuance of guarantees/sales of receivables	242,630	225,448
Settlements	(227,430)	(232,381)
Changes in anticipated loss rate	0
Losses recognized in earnings	(5,133)	(2,395)
Balance at	25,864	15,797
Fair Value, Measurements, Recurring [Member] | Guarantees [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at	4,575	13,478
Issuance of guarantees/sales of receivables	6,061	5,791
Settlements	(5,307)	(14,694)
Changes in anticipated loss rate	(64)
Losses recognized in earnings	0	0
Balance at	$ 5,265	$ 4,575