Impairments - Fair Value Measurements Table (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held for use	$ 103		$ 926
Cost-method investment	34		39
Fair Value, Inputs, Level 2 [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held for use			187	[1]
Fair Value, Inputs, Level 3 [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held for use	103	[1]	739	[1]
Cost-method investment	$ 34	[1]	$ 39	[1]

[1] The income approach was used to measure fair value.