Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 3,063	$ 2,220	$ 2,259
Weighted average number of common shares (in shares)	772,963	799,217	804,680
Effect of dilutive outstanding equity-based awards (in shares)	10,521	11,760	10,236
Weighted average number of diluted common shares (in shares)	783,484	810,977	814,916
Basic EPS (in dollars per share)	$ 3.96	$ 2.78	$ 2.81
Diluted EPS (in dollars per share)	$ 3.91	$ 2.74	$ 2.77
Anti-dilutive awards (in shares)	22	210	5,609