Benefit Plans Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension plans with an accumulated benefit obligation in excess of plan assets:
Fair value of plan assets	$ 77	$ 65
Accumulated benefit obligation	131	113
Pension plans with a projected benefit obligation in excess of plan assets:
Projected benefit obligation	162	138
Pension Plan [Member]
Pension plans with a projected benefit obligation in excess of plan assets:
Fair value of plan assets	$ 83	$ 66