Stockholders' Equity (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2015	Jun. 18, 2014
Stockholders' Equity Note [Abstract]
Preferred stock, shares authorized	5,000,000.0	5,000,000
Common stock, shares authorized	1,150,000,000.000	1,150,000,000			1,150,000,000.000
Common stock, shares issued	940,100,000.0	924,800,000
Aggregate value of common shares authorized to be purchased under share repurchase program	$ 17,500,000,000.0			$ 4,000,000,000.000
Amount of stock repurchased under share repurchase program	$ 3,251,000,000	$ 2,928,000,000	$ 2,769,000,000
Stock repurchase program, aggregate shares repurchased	146,900,000
Average price of shares repurchased under share repurchase program (in dollars per share)	$ 92.67
Cost of shares repurchased under share repurchase program	$ 13,610,000,000