Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Effective income tax rate	32.80%		29.50%	30.10%	33.10%
R&D tax credit		$ 145
Unrecognized tax benefits that could affect earnings within next 12 months	$ 420			$ 420