Income Tax - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Income Tax Examination [Line Items]
Charges (credits) pretax	$ (664)	$ 22	$ (572)	$ 37
Deferred tax assets, valuation allowances relating to net operating losses in certain countries	234		234		256
US statutory federal rate	35.00%	35.00%	35.00%	35.00%
Domestic Country [Member]
Income Tax Examination [Line Items]
Charges (credits) pretax	53	11	53	22
Foreign Country [Member]
Income Tax Examination [Line Items]
Charges (credits) pretax	$ (717)	$ 11	$ (625)	$ 15