Retirement and Deferred Compensation Plans (Fair Value of Benefit Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	$ 1,589	$ 1,420
Corporate Bonds [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	274	249
U.S. Government Bonds [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	280	252
Foreign Government Bonds [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	67	216
State And Municipal Bonds [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	29	28
Common And Preferred Stock [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	599	485
Bulk Annuity Insurance Policy [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	165
Invested Cash [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	106	125
Other Investments [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Fair value of plan assets	$ 69	$ 65