Income Taxes - Schedule of Components of Net Deferred Tax Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Deferred tax assets, Depreciation	$ 185	$ 104
Deferred tax assets, Employee benefits	2,499	2,742
Deferred tax assets, Loss provisions	437	368
Deferred tax assets, Deferred income/expense	87	53
Deferred tax assets, Tax loss carryforwards	2,229	2,186
Deferred tax assets, Tax credit carryforwards	567	508
Deferred tax assets, Derivatives and hedging activities	74	117
Deferred tax assets, Other	310	324
Deferred tax assets, Gross	6,388	6,402
Deferred tax assets, Valuation allowance	(1,804)	(1,400)	(1,398)	(1,268)
Deferred tax assets, net	4,584	5,002
Deferred tax liabilities, Depreciation	1,150	1,015
Deferred tax liabilities, Employee benefits	36	46
Deferred tax liabilities, Loss provisions	14	17
Deferred tax liabilities, Deferred income/expense	188	203
Deferred tax liabilities, Tax loss carryforwards
Deferred tax liabilities, Tax credit carryforwards
Deferred tax liabilities, Derivatives and hedging activities	25	16
Deferred tax liabilities, Other	261	297
Deferred tax liabilities, Gross	1,674	1,594
Deferred tax liabilities, Valuation allowance
Deferred tax liabilities, Net	$ 1,674	$ 1,594