Employee Benefit Plans (Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 243	$ 212
Defined Benefit Plan, Plan Assets, Amount	$ 157	$ 133