Equity (Common Stock - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Equity [Abstract]
Treasury Stock, Shares, Acquired	16,038,791	1,445,864
Treasury Stock, Value, Acquired, Cost Method	$ 858	$ 70
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,800