Income Taxes (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Tax Contingency [Line Items]
Income Tax Expense (Benefit)	$ 207	$ 223
Effective income tax rate	26.30%	31.30%
Income Tax Expense Benefit, Period Increase (Decrease) due to tax settlement	(51)
Unrecognized Tax Benefits, Period Increase (Decrease) due to tax settlement	(59)
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	12
American Taxpayer Relief Act
Income Tax Contingency [Line Items]
Research tax credits		$ 20