Retirement and Deferred Compensation Plans (Fair Value of Benefit Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value of Benefit Plans' Assets [Abstract]
Common and preferred stock	$ 542	$ 554
Cash and invested cash	151	152
Other investments	54	50
Total	1,486	1,570
Fixed Maturity AFS Securities [Member]
Fair Value of Benefit Plans' Assets [Abstract]
Corporate bonds	355	454
U.S. government bonds	207	161
Foreign government bonds	145	166
State and municipal bonds	$ 32	$ 33