Commitments and Contingencies (Details) (USD $)			3 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member]	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member] 2028 [Member]	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member] 2029 [Member]	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member] 2030 [Member]	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member] 2031 [Member]	Sep. 30, 2013 Affiliate Pollution Control and Solid Waste Disposal Bonds [Member] 2032 [Member]
Commitment:
Unfunded commitments under credit facilities with vehicle and industrial equipment dealers	$ 1,321,000,000	$ 1,106,000,000
Minimum lease commitments	67,000,000	74,000,000
Total unfunded commitments	1,388,000,000	1,180,000,000
Guarantor Obligations [Line Items]
Guaranteed Bond Obligations	100,000,000	100,000,000	100,000,000	20,000,000	50,000,000	10,000,000	10,000,000	10,000,000
Guaranty Fee			78,000
Total commitments and guarantees	1,488,000,000	1,280,000,000
Future minimum lease payments under non-cancelable operating leases
2014	10,000,000
2015	18,000,000
2016	17,000,000
2017	12,000,000
2018	7,000,000
Thereafter	3,000,000
Total	67,000,000	74,000,000
Facility lease commitments with affiliate	$ 34,000,000	$ 37,000,000