Income Taxes - Taxes Receivable (Payable) Table (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable	$ 181	$ 599
Income taxes receivable (payable)	143	351
Accounts Receivable - Other [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable	179	597
Other Assets [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes receivable	2	2
Accrued Expense [Member]
Components of Income Tax Receivable (Payable) [Line Items]
Income taxes (payable)	$ (38)	$ (248)