Stock-Based Compensation (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Net cash proceeds from the exercise of stock options	$ 258	$ 299	$ 139
Total intrinsic value of option exercises	158	120	41
Income tax benefit realized from stock option exercises	$ 61	$ 47	$ 16