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Employee Benefits Schedule of Fair Value, Assets (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Pension Plan [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 753 | $ 695 | $ 546
Pension Plan [Member] | Money market funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6 | 5 |
Pension Plan [Member] | Collective trust funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 692 | 632 |
Pension Plan [Member] | Private equity funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6 | 9 |
Pension Plan [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 49 | 49 |
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 49 | 49 |
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 49 | 49 |
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Pension Plan [Member] | Other |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 704 | 646 |
Pension Plan [Member] | Other | Money market funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6 | 5 |
Pension Plan [Member] | Other | Collective trust funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 692 | 632 |
Pension Plan [Member] | Other | Private equity funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6 | 9 |
Other Postretirement Benefit Plans [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 35 | 34 | $ 30
Other Postretirement Benefit Plans [Member] | Money market funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5 | 5 |
Other Postretirement Benefit Plans [Member] | Money Market Funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 4 | 4 |
Other Postretirement Benefit Plans [Member] | Collective trust funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 9 | 8 |
Other Postretirement Benefit Plans [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 3 | 3 |
Other Postretirement Benefit Plans [Member] | Defined Benefit Plan, Equity Securities, Non-US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 9 | 9 |
Other Postretirement Benefit Plans [Member] | US Government Agencies Debt Securities |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5 | 5 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 13 | 13 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 4 | 4 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member] | Defined Benefit Plan, Equity Securities, Non-US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 9 | 9 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 8 | 8 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 3 | 3 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Equity Securities, Non-US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5 | 5 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member] | Money Market Funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member] | Defined Benefit Plan, Equity Securities, US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member] | Defined Benefit Plan, Equity Securities, Non-US |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Other Postretirement Benefit Plans [Member] | Other |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 14 | 13 |
Other Postretirement Benefit Plans [Member] | Other | Money market funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5 | 5 |
Other Postretirement Benefit Plans [Member] | Other | Collective trust funds |  |  |
Equity securities: |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 9 | $ 8 |

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