Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Computation of EPS
Net income available to common shareholders	$ 1,936	$ 1,983	$ 1,563
Basic weighted average shares outstanding	748,010	718,140	703,042
Effect of dilutive outstanding equity-based awards	9,755	10,232	11,321
Diluted weighted average shares outstanding	757,765	728,372	714,363
Basic EPS	$ 2.59	$ 2.76	$ 2.22
Diluted EPS	$ 2.56	$ 2.72	$ 2.19
Anti-dilutive equity-based awards	8,620	14,333	28,456