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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 490	$ 629	$ 930	$ 1,959
Weighted average common shares outstanding — basic	925	913	924	879
Assumed exercise and/or distributions of stock-based awards	2	2	2	4
Weighted average common shares outstanding — diluted	927	915	926	883