Shareholders' Equity (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jul. 17, 2019	Apr. 26, 2018
Treasury Stock, Value, Acquired	$ 105	$ 244
The 2018 Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount				$ 2,000
Treasury Stock, Shares, Acquired	4,100,000	7,800,000
Treasury Stock, Value, Acquired	$ 105	$ 244
2019 Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount			$ 5,000
Common Stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion	50,000
Series A Convertible Preferred Stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion	2,300