Earnings Per Share and Equity - Schedule of Earnings per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 267	$ 638	$ 440	$ 1,331
Weighted average common shares outstanding — basic	924	863	923	862
Assumed exercise and/or distributions of stock-based awards	2	3	3	4
Weighted average common shares outstanding — diluted	926	866	926	866