Shareholders' Equity (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012				$ (2,610)
Other comprehensive loss before reclassifications, net				(253)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss				82
Tax benefit				(28)
Amounts reclassified from accumulated other comprehensive loss, net				54
Total other comprehensive loss	(34)		(196)	(199)		(64)
Balance at June 30, 2013	(2,809)			(2,809)
Change in Fair Value of Investments [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012				0	[1]
Other comprehensive loss before reclassifications, net				13	[1]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss				0	[1]
Tax benefit				0	[1]
Amounts reclassified from accumulated other comprehensive loss, net				0	[1]
Total other comprehensive loss				13	[1]
Balance at June 30, 2013	13	[1]		13	[1]
Change in Fair Value of Derivatives [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012				(28)	[2]
Other comprehensive loss before reclassifications, net				(30)	[2]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss				16	[2]
Tax benefit				(7)	[2]
Amounts reclassified from accumulated other comprehensive loss, net				9	[2]
Total other comprehensive loss				(21)	[2]
Balance at June 30, 2013	(49)	[2]		(49)	[2]
Foreign Currency Translation Adjustments [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012				233
Other comprehensive loss before reclassifications, net				(232)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss				0
Tax benefit				0
Amounts reclassified from accumulated other comprehensive loss, net				0
Total other comprehensive loss				(232)
Balance at June 30, 2013	1			1
Post-Retirement Benefit Obligation [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012				(2,815)	[1]
Other comprehensive loss before reclassifications, net				(4)	[1]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss				66	[1]
Tax benefit				(21)	[1]
Amounts reclassified from accumulated other comprehensive loss, net				45	[1]
Total other comprehensive loss				41	[1]
Balance at June 30, 2013	$ (2,774)	[1]		$ (2,774)	[1]

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

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