Retirement and Deferred Compensation Plans (Fair Value of Benefit Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value of Benefit Plans' Assets [Abstract]
U.S. government mortgage-backed securities		$ 3
Cash and invested cash	$ 19	2
Other investments	8	7
Total	115	118
Fixed Maturity Securities [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Corporate bonds	1	1
U.S. government bonds	$ 87	$ 105