Shareholders' Equity (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	$ (2,610)
Other comprehensive income (loss) before reclassifications, net	(94)
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	100
Tax benefit	(32)
Amounts reclassified from accumulated other comprehensive loss, net	68
Net current period other comprehensive (loss) income	(26)
Balance at September 30, 2013	(2,636)
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 income (loss) before reclassifications, net	12	[1]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	(20)	[1]
Tax benefit	7	[1]
Amounts reclassified from accumulated other comprehensive loss, net	(13)	[1]
Net current period other comprehensive (loss) income	(1)	[1]
Balance at September 30, 2013	(1)	[1]
Change in Fair Value of Derivatives [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(28)	[1]
Other comprehensive income (loss) before reclassifications, net	(24)	[1]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	20	[1]
Tax benefit	(8)	[1]
Amounts reclassified from accumulated other comprehensive loss, net	12	[1]
Net current period other comprehensive (loss) income	(12)	[1]
Balance at September 30, 2013	(40)	[1]
Foreign Currency Translation Adjustments [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	233
Other comprehensive income (loss) before reclassifications, net	(78)
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
Net current period other comprehensive (loss) income	(78)
Balance at September 30, 2013	155
Post-Retirement Benefit Obligation [Member]
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2012	(2,815)	[2]
Other comprehensive income (loss) before reclassifications, net	(4)	[2]
Amounts reclassified from accumulated other comprehensive loss:
Amounts reclassified from accumulated other comprehensive loss	100	[2]
Tax benefit	(31)	[2]
Amounts reclassified from accumulated other comprehensive loss, net	69	[2]
Net current period other comprehensive (loss) income	65	[2]
Balance at September 30, 2013	$ (2,750)	[2]

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

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