Earnings Per Share and Equity - Schedule of Earnings per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 733	$ 823	$ 1,858	$ 1,907
Weighted average common shares outstanding — basic	968	962	967	941
Assumed exercise and/or distributions of stock-based awards	2	3	2	2
Weighted average common shares outstanding — diluted	970	965	969	943