Maximum Potential Amount of Future Fundings as the Primary Obligor for Guarantees and the Liability for Expected Future Fundings (Detail) (Primary Obligor, USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Guarantor Obligations [Line Items]
Maximum Potential Amount of Future Fundings	$ 209
Liability for Guarantees	60
Debt Service
Guarantor Obligations [Line Items]
Maximum Potential Amount of Future Fundings	88
Liability for Guarantees	7
Operating Profit
Guarantor Obligations [Line Items]
Maximum Potential Amount of Future Fundings	106
Liability for Guarantees	51
Other
Guarantor Obligations [Line Items]
Maximum Potential Amount of Future Fundings	15
Liability for Guarantees	$ 2