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Employee Benefit Plans - Defined Benefit Plan, Information about Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
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
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	3,524	4,482
Defined Benefit Plan, Fair Value of Plan Assets, Excluded Investment Payables	46	46
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	3,524	4,482
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	3,573	3,524
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	163
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	163
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	198	163
Pension Plan [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	2,299
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	2,299
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	2,313	2,299
Pension Plan [Member] | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	198	251
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	198	251
Realized gains (losses), net	(3)	0
Changes in unrealized gains (losses), net	9	(35)
Purchases	13	5
Sales	(30)	(18)
Transfers into Level 3 [2]	5	3
Transfers out of Level 3 [2]	(2)	(8)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	190	198
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	3,478
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	3,478
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	$ 3,527	$ 3,478
Pension Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	19.00%	27.00%
Pension Plan [Member] | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	81.00%	73.00%
Pension Plan [Member] | Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	$ 155
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	155
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	187	$ 155
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	155
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	155
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	187	155
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	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] | 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	1,822
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1,822
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	1,679	1,822
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	1,791
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1,791
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	1,643	1,791
Pension Plan [Member] | Corporate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	31	42
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	31	42
Realized gains (losses), net	0	0
Changes in unrealized gains (losses), net	2	(10)
Purchases	0	1
Sales	0	(2)
Transfers into Level 3 [2]	5	3
Transfers out of Level 3 [2]	(2)	(3)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	36	31
Pension Plan [Member] | Residential mortgage-backed securities ("RMBS")
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	115
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	115
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	111	115
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	115
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	115
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	111	115
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
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] | U.S. Treasuries
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	271	165
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	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] | U.S. Treasuries | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	271	165
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	26
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	26
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	21	26
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	25
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	25
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	11	25
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	1	2
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1	2
Realized gains (losses), net	0	0
Changes in unrealized gains (losses), net	(1)	0
Purchases	10	0
Sales	0	0
Transfers into Level 3 [2]	0	0
Transfers out of Level 3 [2]	0	(1)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	10	1
Pension Plan [Member] | CMBS
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	58
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	58
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	50	58
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	57
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	57
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	49	57
Pension Plan [Member] | CMBS | 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	1	1
Pension Plan [Member] | Other Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	139
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	139
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	160	139
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	139
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	139
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	160	139
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	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
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	143	165
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	165	202
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	165	202
Realized gains (losses), net	(3)	0
Changes in unrealized gains (losses), net	8	(25)
Purchases	3	4
Sales	(30)	(16)
Transfers into Level 3 [2]	0	0
Transfers out of Level 3 [2]	0	0
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	143	165
Pension Plan [Member] | Domestic
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	8
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	8
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	34	8
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	8
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	8
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	11	8
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	23	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	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	45	7
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	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 | 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	45	7
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	2,660
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	2,660
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	2,701	2,660
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	163
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	163
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	198	163
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	2,299
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	2,299
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	2,313	2,299
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	198
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	198
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	190	198
Pension Plan [Member] | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	818
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	818
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	826	818
Pension Plan [Member] | Other investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1	5
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1	5
Realized gains (losses), net	0	0
Changes in unrealized gains (losses), net	0	0
Purchases	0	0
Sales	0	0
Transfers into Level 3 [2]	0	0
Transfers out of Level 3 [2]	0	(4)
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	30	51
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	30	51
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	18	30
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	25
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	25
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	16	25
Other Postretirement Benefits Plan [Member] | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	5
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	5
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	2	5
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%
Other Postretirement Benefits Plan [Member] | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	100.00%	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	$ 25
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	25
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	16	$ 25
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	25
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	25
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	16	25
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] | Residential mortgage-backed securities ("RMBS")
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] | 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	1
Pension Plan Asset Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Amount, Beginning Balance	1
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Minimum | Pension Plan [Member] | Equity Securities [Member]
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Defined Benefit Plan Disclosure [Line Items]
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Maximum | Pension Plan [Member] | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
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Maximum | Other Postretirement Benefits Plan [Member] | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
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