Total Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Apr. 20, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Treasury Shares
Authorized repurchase amount of outstanding common stock		$ 3,100		$ 3,100
Dividends declared per common share	$ 0.15	$ 0.15	$ 0.1	$ 0.4	$ 0.25
Common stock repurchased		$ 625	$ 195	$ 1,500	$ 629
Nonredeemable Noncontrolling Interests
Nonredeemable noncontrolling interests		$ 1,133		$ 1,133		$ 1,204