Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 527	$ 488
Weighted average number of common shares (in shares)	781,193	721,639
Effect of dilutive outstanding equity-based awards (in shares)	8,983	9,872
Weighted average number of diluted common shares (in shares)	790,176	731,511
Basic EPS (in dollars per share)	$ 0.67	$ 0.68
Diluted EPS (in dollars per share)	$ 0.67	$ 0.67
Anti-dilutive awards (in shares)	10,711	11,543