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Employee Benefit Plans - Defined Benefit Plan, Information about Plan Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Significant Unobservable Inputs (Level 3)    
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Settlements $ 0 $ 0
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 0
Foreign government/government agencies | 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 0
Pension Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4,482 4,363
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4,482 4,363
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 3,524 4,482
Defined Benefit Plan, Fair Value of Plan Assets, Excluded Investment Payables 46 51
Pension Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 501  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 501  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 163 501
Pension Plan [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,908  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,908  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 2,299 2,908
Pension Plan [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 251 210
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 251 210
Realized gains, net 0 (3)
Changes in unrealized gains (losses), net (35) 0
Purchases 5 66
Sales (18) (23)
Transfers into Level 3 3 2
Transfers out of Level 3 (8) (1)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 198 251
Pension Plan [Member] | Fair Value, Inputs, Level 1, 2 and 3    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4,431  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4,431  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance $ 3,478 $ 4,431
Pension Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 27.00% 35.00%
Pension Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 73.00% 65.00%
Pension Plan [Member] | Short-term Investments [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance $ 149  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 149  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 155 $ 149
Pension Plan [Member] | Short-term Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 120  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 120  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 155 120
Pension Plan [Member] | Short-term Investments [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 29  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 29  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 29
Pension Plan [Member] | Short-term Investments [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Corporate    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,375  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,375  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1,822 2,375
Pension Plan [Member] | Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Corporate | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,333  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,333  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1,791 2,333
Pension Plan [Member] | Corporate | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 42 39
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 42 39
Realized gains, net 0 0
Changes in unrealized gains (losses), net (10) 0
Purchases 1 6
Sales (2) (5)
Transfers into Level 3 3 2
Transfers out of Level 3 (3) 0
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 31 42
Pension Plan [Member] | Residential mortgage-backed securities ("RMBS")    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 98  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 98  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 115 98
Pension Plan [Member] | Residential mortgage-backed securities ("RMBS") | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Residential mortgage-backed securities ("RMBS") | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 98  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 98  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 115 98
Pension Plan [Member] | Residential mortgage-backed securities ("RMBS") | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0 1
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0 1
Realized gains, net 0 0
Changes in unrealized gains (losses), net 0 0
Purchases 0 0
Sales 0 0
Transfers into Level 3 0 0
Transfers out of Level 3 0 (1)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | U.S. Treasuries    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 192  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 192  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 165 192
Pension Plan [Member] | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 23  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 23  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 23
Pension Plan [Member] | U.S. Treasuries | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 169  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 169  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 165 169
Pension Plan [Member] | U.S. Treasuries | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Foreign government/government agencies    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 40  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 40  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 26 40
Pension Plan [Member] | Foreign government/government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Foreign government/government agencies | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 38  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 38  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 25 38
Pension Plan [Member] | Foreign government/government agencies | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2 9
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2 9
Realized gains, net 0 0
Changes in unrealized gains (losses), net 0 0
Purchases 0 0
Sales 0 (7)
Transfers into Level 3 0 0
Transfers out of Level 3 (1) 0
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 2
Pension Plan [Member] | CMBS    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 60  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 60  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 58 60
Pension Plan [Member] | CMBS | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | CMBS | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 56  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 56  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 57 56
Pension Plan [Member] | CMBS | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 4  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 4
Pension Plan [Member] | Other Fixed Income [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 186  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 186  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 139 186
Pension Plan [Member] | Other Fixed Income [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Other Fixed Income [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 185  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 185  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 139 185
Pension Plan [Member] | Other Fixed Income [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Pension Plan [Member] | Mortgage loans    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 202  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 202  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 165 202
Pension Plan [Member] | Mortgage loans | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Mortgage loans | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Mortgage loans | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 202 161
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 202 161
Realized gains, net 0 (3)
Changes in unrealized gains (losses), net (25) 0
Purchases 4 55
Sales (16) (11)
Transfers into Level 3 0 0
Transfers out of Level 3 0 0
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 165 202
Pension Plan [Member] | Domestic    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 237  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 237  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 8 237
Pension Plan [Member] | Domestic | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 237  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 237  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 8 237
Pension Plan [Member] | Domestic | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Domestic | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | International    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 121  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 121  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 7 121
Pension Plan [Member] | International | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 121  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 121  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 121
Pension Plan [Member] | International | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 7 0
Pension Plan [Member] | International | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Pension Plan [Member] | Total pension plan assets at fair value, in the fair value hierarchy    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 3,660  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 3,660  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 2,660 3,660
Pension Plan [Member] | Total pension plan assets at fair value, in the fair value hierarchy | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 501  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 501  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 163 501
Pension Plan [Member] | Total pension plan assets at fair value, in the fair value hierarchy | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,908  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 2,908  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 2,299 2,908
Pension Plan [Member] | Total pension plan assets at fair value, in the fair value hierarchy | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 251  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 251  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 198 251
Pension Plan [Member] | Private Market Alternatives    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 572  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 572  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 666 572
Pension Plan [Member] | Hedge funds    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 199  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 199  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 152 199
Pension Plan [Member] | Other investments | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 5 0
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 5 0
Realized gains, net 0 0
Changes in unrealized gains (losses), net 0 0
Purchases 0 5
Sales 0 0
Transfers into Level 3 0 0
Transfers out of Level 3 (4) 0
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 5
Pension Plan [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 1
Other Postretirement Benefits Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 51 63
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 51 63
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 30 51
Other Postretirement Benefits Plan [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 19  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 19  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 25 19
Other Postretirement Benefits Plan [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 32  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 32  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 5 32
Other Postretirement Benefits Plan [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance $ 0 $ 0
Other Postretirement Benefits Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 25.00% 25.00%
Other Postretirement Benefits Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 75.00% 75.00%
Other Postretirement Benefits Plan [Member] | Short-term Investments [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance $ 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 25 $ 1
Other Postretirement Benefits Plan [Member] | Short-term Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 25 1
Other Postretirement Benefits Plan [Member] | Short-term Investments [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Short-term Investments [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Corporate    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 11  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 11  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 11
Other Postretirement Benefits Plan [Member] | Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Corporate | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 11  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 11  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 11
Other Postretirement Benefits Plan [Member] | Corporate | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Residential mortgage-backed securities ("RMBS")    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 7  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 7  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 7
Other Postretirement Benefits Plan [Member] | Residential mortgage-backed securities ("RMBS") | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Residential mortgage-backed securities ("RMBS") | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 7  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 7  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 1 7
Other Postretirement Benefits Plan [Member] | Residential mortgage-backed securities ("RMBS") | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | U.S. Treasuries    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 14  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 14  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 4 14
Other Postretirement Benefits Plan [Member] | U.S. Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Other Postretirement Benefits Plan [Member] | U.S. Treasuries | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 13  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 13  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 4 13
Other Postretirement Benefits Plan [Member] | U.S. Treasuries | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Foreign government/government agencies    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Other Postretirement Benefits Plan [Member] | Foreign government/government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Other Postretirement Benefits Plan [Member] | Foreign government/government agencies | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0
Other Postretirement Benefits Plan [Member] | Foreign government/government agencies | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | CMBS    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | CMBS | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | CMBS | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | CMBS | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Other Fixed Income [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Other Postretirement Benefits Plan [Member] | Other Fixed Income [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Other Fixed Income [Member] | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 1  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 1
Other Postretirement Benefits Plan [Member] | Other Fixed Income [Member] | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Large-cap    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 16  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 16  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 16
Other Postretirement Benefits Plan [Member] | Large-cap | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 16  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 16  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 16
Other Postretirement Benefits Plan [Member] | Large-cap | Significant Observable Inputs (Level 2)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Large-cap | Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance 0 0
Other Postretirement Benefits Plan [Member] | Defined Benefit Plan, Equity Securities, Common Stock [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)    
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance 0  
Defined Benefit Plan, Plan Assets, Amount, Ending Balance $ 0 $ 0
Minimum | Pension Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%  
Minimum | Pension Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 75.00%  
Minimum | Pension Plan [Member] | Alternative assets    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%  
Minimum | Other Postretirement Benefits Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%  
Minimum | Other Postretirement Benefits Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 100.00%  
Minimum | Other Postretirement Benefits Plan [Member] | Alternative assets    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%  
Maximum | Pension Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 20.00%  
Maximum | Pension Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 95.00%  
Maximum | Pension Plan [Member] | Alternative assets    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 25.00%  
Maximum | Other Postretirement Benefits Plan [Member] | Equity Securities [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%  
Maximum | Other Postretirement Benefits Plan [Member] | Fixed income securities    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 100.00%  
Maximum | Other Postretirement Benefits Plan [Member] | Alternative assets    
Defined Benefit Plan Disclosure [Line Items]    
Target asset allocation 0.00%