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Employee Benefit Plans - Defined Benefit Plan, Information about Plan Assets (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017
Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | $ 0 | $ (6) |  |
Equity securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 40.00% |
Fixed income securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 60.00% |
Corporate | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | 0 | 0 |  |
Residential mortgage-backed securities (RMBS) | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | 0 | (5) |  |
Foreign government | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | 0 | 0 |  |
Mortgage loans | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | 0 | 0 |  |
Other investments | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Settlements | 0 | (1) |  |
Pension Benefits |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 3,563 |  |  |
Fair value of plan assets - end of year | 3,345 | 3,563 |  |
Plan assets at fair value | 3,345 | 3,563 | $ 3,345 | $ 3,563
Excluded investment payables |  |  | 1 | 1
Defined Benefit Plan, Fair Value of Plan Assets, Excluded Interest Receivables |  |  |  | 30
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 973 |  |  |
Fair value of plan assets - end of year | 739 | 973 |  |
Plan assets at fair value | 739 | 973 | 739 | 973
Pension Benefits | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 2,049 |  |  |
Fair value of plan assets - end of year | 1,997 | 2,049 |  |
Plan assets at fair value | 1,997 | 2,049 | 1,997 | 2,049
Pension Benefits | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 161 | 167 |  |
Realized gains,net | 0 | 2 |  |
Changes in unrealized gains (losses), net | (2) | 6 |  |
Purchases | 6 | 36 |  |
Sales | (14) | (35) |  |
Transfers into Level 3 | 0 | 2 |  |
Transfers out of Level 3 |  | (11) |  |
Fair value of plan assets - end of year | 151 | 161 |  |
Plan assets at fair value | 151 | 161 | 151 | 161
Pension Benefits | Short-term Investments [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 110 | 189
Pension Benefits | Short-term Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 50 | 21
Pension Benefits | Short-term Investments [Member] | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 60 | 168
Pension Benefits | Short-term Investments [Member] | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 |  |  |
Fair value of plan assets - end of year | 1 | 1 |  |
Plan assets at fair value | 1 | 1 | $ 1 | 1
Pension Benefits | Equity securities | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 35.00% |
Pension Benefits | Equity securities | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 5.00% |
Pension Benefits | Fixed income securities | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 70.00% |
Pension Benefits | Fixed income securities | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 50.00% |
Pension Benefits | Alternative assets | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 45.00% |
Pension Benefits | Alternative assets | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 0.00% |
Pension Benefits | Corporate |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | $ 1,677 | 1,563
Pension Benefits | Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Corporate | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 1,663 | 1,549
Pension Benefits | Corporate | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 14 | 13 |  |
Realized gains,net | 0 | 0 |  |
Changes in unrealized gains (losses), net | (1) | 2 |  |
Purchases | 5 | 11 |  |
Sales | (4) | (12) |  |
Transfers into Level 3 | 0 | 0 |  |
Fair value of plan assets - end of year | 14 | 14 |  |
Plan assets at fair value in the fair value hierarchy |  |  | 14 | 14
Plan assets at fair value | 14 | 14 | 14 | 14
Pension Benefits | Residential mortgage-backed securities (RMBS) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 63 | 30
Pension Benefits | Residential mortgage-backed securities (RMBS) | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Residential mortgage-backed securities (RMBS) | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 62 | 28
Pension Benefits | Residential mortgage-backed securities (RMBS) | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 2 | 10 |  |
Realized gains,net | 0 | 0 |  |
Changes in unrealized gains (losses), net | 0 | 0 |  |
Purchases | 0 | 1 |  |
Sales | (1) | (4) |  |
Transfers into Level 3 | 0 | 0 |  |
Transfers out of Level 3 | 0 |  |  |
Fair value of plan assets - end of year | 1 | 2 |  |
Plan assets at fair value in the fair value hierarchy |  |  | 1 | 2
Plan assets at fair value | 2 | 2 | 1 | 2
Pension Benefits | U.S. Treasuries |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 130 | 77
Pension Benefits | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 10 | 3
Pension Benefits | U.S. Treasuries | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 120 | 74
Pension Benefits | U.S. Treasuries | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Foreign government |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 17 | 17
Pension Benefits | Foreign government | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Foreign government | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 15 | 16
Pension Benefits | Foreign government | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 | 1 |  |
Realized gains,net | 0 | 0 |  |
Changes in unrealized gains (losses), net | 0 | 0 |  |
Purchases | 1 | 0 |  |
Sales | 0 | 0 |  |
Transfers into Level 3 | 0 | 0 |  |
Transfers out of Level 3 | 0 |  |  |
Fair value of plan assets - end of year | 2 | 1 |  |
Plan assets at fair value in the fair value hierarchy |  |  | 2 | 1
Plan assets at fair value | 2 | 1 | 2 | 1
Pension Benefits | CMBS |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 22 | 30
Pension Benefits | CMBS | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | CMBS | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 22 | 28
Pension Benefits | CMBS | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 2
Pension Benefits | Other Fixed Income [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 53 | 99
Pension Benefits | Other Fixed Income [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Other Fixed Income [Member] | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 52 | 97
Pension Benefits | Other Fixed Income [Member] | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 1 | 2
Pension Benefits | Mortgage loans |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 133 | 140
Pension Benefits | Mortgage loans | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Mortgage loans | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Mortgage loans | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 140 | 121 |  |
Realized gains,net | 0 | 0 |  |
Changes in unrealized gains (losses), net | (1) | 2 |  |
Purchases | 0 | 17 |  |
Sales | (6) | 0 |  |
Transfers into Level 3 | 0 | 0 |  |
Transfers out of Level 3 | 0 |  |  |
Fair value of plan assets - end of year | 133 | 140 |  |
Plan assets at fair value in the fair value hierarchy |  |  | 133 | 140
Plan assets at fair value | 140 | 140 | 133 | 140
Pension Benefits | Other investments | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 4 | 22 |  |
Realized gains,net | 0 | 2 |  |
Changes in unrealized gains (losses), net | 0 | 2 |  |
Purchases | 0 | 7 |  |
Sales | (3) | (19) |  |
Transfers into Level 3 | 0 | 2 |  |
Transfers out of Level 3 |  | (11) |  |
Fair value of plan assets - end of year | 1 | 4 |  |
Plan assets at fair value | 4 | 4 | 1 | 4
Pension Benefits | Large-cap domestic |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 379 | 684
Pension Benefits | Large-cap domestic | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 376 | 595
Pension Benefits | Large-cap domestic | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 3 | 89
Pension Benefits | Large-cap domestic | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Mid-cap domestic |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  |  | 11
Pension Benefits | Mid-cap domestic | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  |  | 11
Pension Benefits | Mid-cap domestic | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  |  | 0
Pension Benefits | Mid-cap domestic | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  |  | 0
Pension Benefits | International |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 303 | 343
Pension Benefits | International | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 303 | 343
Pension Benefits | International | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | International | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 0 | 0
Pension Benefits | Total pension plan assets at fair value, in the fair value hierarchy |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 2,887 | 3,183
Pension Benefits | Total pension plan assets at fair value, in the fair value hierarchy | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 739 | 973
Pension Benefits | Total pension plan assets at fair value, in the fair value hierarchy | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 1,997 | 2,049
Pension Benefits | Total pension plan assets at fair value, in the fair value hierarchy | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at fair value in the fair value hierarchy |  |  | 151 | 161
Pension Benefits | Private Market Alternatives |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  | 272 | 168
Pension Benefits | Private Market Alternatives | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Pension Benefits | Private Market Alternatives | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Pension Benefits | Private Market Alternatives | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Pension Benefits | Hedge funds |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  | 186 | 212
Pension Benefits | Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Pension Benefits | Hedge funds | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Pension Benefits | Hedge funds | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Plan assets at net asset value |  |  |  |
Other Postretirement Benefits |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 113 |  |  |
Fair value of plan assets - end of year | 85 | 113 |  |
Plan assets at fair value | 85 | 113 | 85 | 113
Excluded investment payables |  |  | 1 | 0
Defined Benefit Plan, Fair Value of Plan Assets, Excluded Interest Receivables |  |  |  | 1
Other Postretirement Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 35 |  |  |
Fair value of plan assets - end of year | 33 | 35 |  |
Plan assets at fair value | 33 | 35 | 33 | 35
Other Postretirement Benefits | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 77 |  |  |
Fair value of plan assets - end of year | 52 | 77 |  |
Plan assets at fair value | 52 | 77 | 52 | 77
Other Postretirement Benefits | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 |  |  |
Fair value of plan assets - end of year |  | 1 |  |
Plan assets at fair value | 1 | 1 |  | 1
Other Postretirement Benefits | Short-term Investments [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 4 |  |  |
Fair value of plan assets - end of year | 4 | 4 |  |
Plan assets at fair value | 4 | 4 | 4 | 4
Other Postretirement Benefits | Short-term Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 4 |  |  |
Fair value of plan assets - end of year | 4 | 4 |  |
Plan assets at fair value | 4 | 4 | 4 | 4
Other Postretirement Benefits | Short-term Investments [Member] | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 0 |  |  |
Fair value of plan assets - end of year | 0 | 0 |  |
Plan assets at fair value | 0 | 0 | 0 | 0
Other Postretirement Benefits | Defined Benefit Plan, Equity Securities, Common Stock [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 0 |  |  |
Fair value of plan assets - end of year | 0 | 0 |  |
Plan assets at fair value | 0 | 0 | $ 0 | 0
Other Postretirement Benefits | Equity securities | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 45.00% |
Other Postretirement Benefits | Equity securities | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 15.00% |
Other Postretirement Benefits | Fixed income securities | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 85.00% |
Other Postretirement Benefits | Fixed income securities | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 55.00% |
Other Postretirement Benefits | Alternative assets | Maximum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 0.00% |
Other Postretirement Benefits | Alternative assets | Minimum |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Target asset allocation |  |  | 0.00% |
Other Postretirement Benefits | Corporate |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 25 |  |  |
Fair value of plan assets - end of year | 19 | 25 |  |
Plan assets at fair value | 19 | 25 | $ 19 | 25
Other Postretirement Benefits | Corporate | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 25 |  |  |
Fair value of plan assets - end of year | 19 | 25 |  |
Plan assets at fair value | 19 | 25 | 19 | 25
Other Postretirement Benefits | Corporate | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 0 | 1 |  |
Purchases |  | 1 |  |
Sales |  | 2 |  |
Fair value of plan assets - end of year |  | 0 |  |
Plan assets at fair value | 0 | 1 |  | 0
Other Postretirement Benefits | Residential mortgage-backed securities (RMBS) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 17 |  |  |
Fair value of plan assets - end of year | 15 | 17 |  |
Plan assets at fair value | 15 | 17 | 15 | 17
Other Postretirement Benefits | Residential mortgage-backed securities (RMBS) | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 17 |  |  |
Fair value of plan assets - end of year | 15 | 17 |  |
Plan assets at fair value | 15 | 17 | 15 | 17
Other Postretirement Benefits | Residential mortgage-backed securities (RMBS) | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
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Settlements |  | 1 |  |
Fair value of plan assets - end of year |  | 0 |  |
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Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
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Fair value of plan assets - end of year | 19 | 26 |  |
Plan assets at fair value | 19 | 26 | 19 | 26
Other Postretirement Benefits | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
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Fair value of plan assets - end of year | 6 | 1 |  |
Plan assets at fair value | 6 | 1 | 6 | 1
Other Postretirement Benefits | U.S. Treasuries | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 25 |  |  |
Fair value of plan assets - end of year | 13 | 25 |  |
Plan assets at fair value | 13 | 25 | 13 | 25
Other Postretirement Benefits | Foreign government |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 |  |  |
Fair value of plan assets - end of year | 1 | 1 |  |
Plan assets at fair value | 1 | 1 | 1 | 1
Other Postretirement Benefits | Foreign government | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 |  |  |
Fair value of plan assets - end of year | 1 | 1 |  |
Plan assets at fair value | 1 | 1 | 1 | 1
Other Postretirement Benefits | CMBS |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 5 |  |  |
Fair value of plan assets - end of year | 2 | 5 |  |
Plan assets at fair value | 2 | 5 | 2 | 5
Other Postretirement Benefits | CMBS | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 5 |  |  |
Fair value of plan assets - end of year | 2 | 5 |  |
Plan assets at fair value | 2 | 5 | 2 | 5
Other Postretirement Benefits | Other Fixed Income [Member] |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 5 |  |  |
Fair value of plan assets - end of year | 2 | 5 |  |
Plan assets at fair value | 2 | 5 | 2 | 5
Other Postretirement Benefits | Other Fixed Income [Member] | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 4 |  |  |
Fair value of plan assets - end of year | 2 | 4 |  |
Plan assets at fair value | 2 | 4 | 2 | 4
Other Postretirement Benefits | Other Fixed Income [Member] | Significant Unobservable Inputs (Level 3) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 1 |  |  |
Purchases |  | 1 |  |
Sales | 1 |  |  |
Transfers out of Level 3 |  | 1 |  |
Fair value of plan assets - end of year | 0 | 1 |  |
Plan assets at fair value | 1 | 1 | 0 | 1
Other Postretirement Benefits | Large-cap |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 30 |  |  |
Fair value of plan assets - end of year | 23 | 30 |  |
Plan assets at fair value | 23 | 30 | 23 | 30
Other Postretirement Benefits | Large-cap | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 30 |  |  |
Fair value of plan assets - end of year | 23 | 30 |  |
Plan assets at fair value | 23 | 30 | 23 | 30
Other Postretirement Benefits | Large-cap | Significant Observable Inputs (Level 2) |  |  |  |
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3) |  |  |  |
Fair value of plan assets - beginning of year | 0 |  |  |
Fair value of plan assets - end of year | 0 | 0 |  |
Plan assets at fair value | $ 0 | $ 0 | $ 0 | $ 0

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