Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 745	$ 378
Weighted average number of common shares (in shares)	779,617	809,903
Effect of dilutive outstanding equity-based awards (in shares)	11,388	12,816
Weighted average number of diluted common shares (in shares)	791,005	822,719
Basic EPS (in dollars per share)	$ 0.96	$ 0.47
Diluted EPS (in dollars per share)	$ 0.94	$ 0.46
Anti-dilutive awards (in shares)	90	295