Equity (Common Stock - Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	May 22, 2018	Nov. 01, 2017
Equity [Abstract]
Treasury Stock, Shares, Acquired	45,540,491	34,354,967
Treasury Stock, Value, Acquired, Cost Method	$ 2,156	$ 1,810
Stock Repurchase Program, Authorized Amount			$ 1,500	$ 2,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,100