Shareholders' Equity (Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stockholders' Equity Note [Abstract]
Gain on cash flow hedges, gross amount	$ (23)	$ (81)	$ 89
Gain on cash flow hedges, provision (benefit) for income tax	3	22	(23)
Gain on cash flow hedges, net amount	(20)	(59)	66
Unrealized gains on securities, gross amount	6	(1)	1
Unrealized gains on securities, provision (benefit) for income tax	(2)	0	0
Unrealized gains on securities, net amount	4	(1)	1
Foreign currency translation adjustments, gross amount	141	(89)	308
Foreign currency translation adjustments, provision (benefit) for income tax	130	18	(29)
Foreign currency translation adjustments, net amount	271	(71)	279
Change in retirement plans' funded status, gross amount	(1,149)	(1,129)	(878)
Change in retirement plans' funded status, provision (benefit) for income tax	431	384	303
Change in retirement plans' funded status, net amount	(718)	(745)	(575)
Other comprehensive loss, gross amount	(1,025)	(1,300)	(480)
Other comprehensive loss, provision (benefit) for income tax	562	424	251
Other comprehensive loss, net amount	$ (463)	$ (876)	$ (229)