Equity (Common Stock Repurchase Authorization) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Nov. 01, 2018	May 22, 2018	Dec. 01, 2017
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount		$ 2,000	$ 1,500	$ 2,000
November2018Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 770
May2018Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	0
November2017Authorization [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 0