Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Disclosure [Abstract]
Net income tax payments/(refunds)				$ 410	$ 57	$ 360
Effective income tax rate				34.00%	25.60%	26.50%
Income tax charge (benefit) recorded	(397)	(371)	150
U.S. federal statutory tax				35.00%	35.00%	35.00%
Net deferred tax assets related to Accumulated other comprehensive loss	9,743			10,210	9,743
U.S. deferred income taxes and foreign withholding tax				49
Accrued income tax-related interest	48			11	48
Accrued income tax-related penalties	10			11	10
Amounts of interest (benefit)/expense				(43)	(94)	(105)
Unrecognized tax benefits	939	1,198		1,055	939	1,198	1,787
Unrecognized tax benefits that would affect the effective tax rate, if recognized	$ 838	$ 1,074		$ 945	$ 838	$ 1,074