Disclosures about Fair Value of Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2014	Jun. 30, 2014 Five-year Senior Unsecured Notes [Member]	Sep. 30, 2013 Five-year Senior Unsecured Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, average life from purchase to sale	17 days
Issuance of senior unsecured notes		$ 25	$ 63

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant