Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Tax Contingency [Line Items]
Federal and foreign income tax expense	$ 236	$ 247	$ 459	$ 497
Effective income tax rate	32.60%	34.00%	32.00%	33.50%
Research tax credits			23
Forecast
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Period Increase (Decrease)			80
Income Tax Expense Benefit, Period Increase (Decrease)			$ 50