Shareholders' Equity (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	$ (2,610)
Other comprehensive loss before reclassifications, net	(196)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	46
Tax benefit	(15)
Amounts reclassified from accumulated other comprehensive loss, net	31
Total other comprehensive (loss) income	(165)		132
Balance at March 31, 2013	(2,775)
Change in Fair Value of Derivatives
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(28)	[1]
Other comprehensive loss before reclassifications, net	(22)	[1]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	13	[1]
Tax benefit	(5)	[1]
Amounts reclassified from accumulated other comprehensive loss, net	8	[1]
Total other comprehensive (loss) income	(14)	[1]
Balance at March 31, 2013	(42)	[1]
Foreign Currency Translation Adjustments
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	233	[2]
Other comprehensive loss before reclassifications, net	(174)	[2]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	0	[2]
Tax benefit	0
Amounts reclassified from accumulated other comprehensive loss, net	0
Total other comprehensive (loss) income	(174)	[2]
Balance at March 31, 2013	59	[2]
Post-Retirement Benefit Obligation
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(2,815)	[3]
Other comprehensive loss before reclassifications, net	0	[3]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	33	[3]
Tax benefit	(10)	[3]
Amounts reclassified from accumulated other comprehensive loss, net	23	[3]
Total other comprehensive (loss) income	23	[3]
Balance at March 31, 2013	$ (2,792)	[3]

[1] Reclassifications from Accumulated other comprehensive loss are recorded in Other general expense or Other income

[2] Reclassifications from Accumulated other comprehensive loss are recorded in Other income

[3] Reclassifications from Accumulated other comprehensive loss are recorded in Compensation and benefits