Pension and Postretirement Health Care Benefits (Details) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024 USD ($)		Dec. 31, 2023 USD ($)		Dec. 31, 2022 USD ($)
Pension Benefits [Abstract]
annual interest crediting rates			4.90		4.72		4.89
Target Pension Asset Allocations [Abstract]
transferred			$ 0		$ 0
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation			13		12
Net benefit cost recognized for financial reporting			2		2
Pension Plan [Member]
Pension Benefits [Abstract]
Total benefit obligation			2,752		2,943		$ 2,871
Defined Benefit Plan, Plan Assets, Amount			2,504	[1]	2,690	[1]	2,685
Net benefit cost recognized for financial reporting			$ 79		$ 74		$ 114
Expected average long-term rate of return on assets (as a percent)			6.93%		6.93%		6.49%
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			100.00%		100.00%
Pension Plan [Member] | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 142		$ 759
Pension Plan [Member] | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		662		692
Pension Plan [Member] | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		6		4
Pension Plan [Member] | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		1,694		1,235
Pension Plan [Member] | Cash
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 117		$ 233
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			2.00%		2.00%
Pension Plan [Member] | Cash | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 117		$ 233
Pension Plan [Member] | Cash | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Cash | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Cash | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Commingled Funds
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		1,694		1,726
Pension Plan [Member] | Commingled Funds | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		491
Pension Plan [Member] | Commingled Funds | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Commingled Funds | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Commingled Funds | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		1,694		1,235
Pension Plan [Member] | Debt Securities
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		662		687
Pension Plan [Member] | Debt Securities | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Debt Securities | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		656		683
Pension Plan [Member] | Debt Securities | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		6		4
Pension Plan [Member] | Debt Securities | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Equity Securities
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 25		$ 35
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			31.00%		31.00%
Pension Plan [Member] | Equity Securities | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 25		$ 35
Pension Plan [Member] | Equity Securities | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Equity Securities | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Equity Securities | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Other
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		6		9
Pension Plan [Member] | Other | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Other | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		6		9
Pension Plan [Member] | Other | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		0		0
Pension Plan [Member] | Other | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[1]		$ 0		$ 0
Pension Plan [Member] | Long-duration fixed income and interest rate swap securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			38.00%		38.00%
Pension Plan [Member] | Alternative investments
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			20.00%		20.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			9.00%		9.00%
Other Postretirement Benefits Plan [Member]
Pension Benefits [Abstract]
Total benefit obligation			$ 427		$ 394		$ 405
Defined Benefit Plan, Plan Assets, Amount			344	[2]	356	[2]	364
Net benefit cost recognized for financial reporting			$ 7		$ 6		$ (2)
Expected average long-term rate of return on assets (as a percent)			5.00%		5.00%		4.10%
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			100.00%		100.00%
Other Postretirement Benefits Plan [Member] | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 35		$ 55
Other Postretirement Benefits Plan [Member] | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		241		228
Other Postretirement Benefits Plan [Member] | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		1
Other Postretirement Benefits Plan [Member] | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		68		72
Other Postretirement Benefits Plan [Member] | Cash
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 35		$ 33
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			3.00%		1.00%
Other Postretirement Benefits Plan [Member] | Cash | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 35		$ 33
Other Postretirement Benefits Plan [Member] | Cash | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Cash | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Cash | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Commingled Funds
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		68		94
Other Postretirement Benefits Plan [Member] | Commingled Funds | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		22
Other Postretirement Benefits Plan [Member] | Commingled Funds | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Commingled Funds | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Commingled Funds | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		68		72
Other Postretirement Benefits Plan [Member] | Debt Securities
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		201		188
Other Postretirement Benefits Plan [Member] | Debt Securities | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Debt Securities | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		201		187
Other Postretirement Benefits Plan [Member] | Debt Securities | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		1
Other Postretirement Benefits Plan [Member] | Debt Securities | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 0		$ 0
Other Postretirement Benefits Plan [Member] | Equity Securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			25.00%		9.00%
Other Postretirement Benefits Plan [Member] | Other
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 0		$ 1
Other Postretirement Benefits Plan [Member] | Other | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Other | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		1
Other Postretirement Benefits Plan [Member] | Other | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Other | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 0		$ 0
Other Postretirement Benefits Plan [Member] | Long-duration fixed income and interest rate swap securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			0.00%		0.00%
Other Postretirement Benefits Plan [Member] | Alternative investments
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			11.00%		13.00%
Other Postretirement Benefits Plan [Member] | Short-to-intermediate fixed income securities
Target Pension Asset Allocations [Abstract]
Target pension asset allocations (as a percent)			61.00%		77.00%
Other Postretirement Benefits Plan [Member] | Insurance contracts
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 40		$ 40
Other Postretirement Benefits Plan [Member] | Insurance contracts | Level 1
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Insurance contracts | Level 2
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		40		40
Other Postretirement Benefits Plan [Member] | Insurance contracts | Level 3
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		0		0
Other Postretirement Benefits Plan [Member] | Insurance contracts | Fair Value Measured at Net Asset Value Per Share
Pension Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Amount	[2]		$ 0		$ 0
Forecast | Pension Plan [Member]
Pension Benefits [Abstract]
Expected average long-term rate of return on assets for next fiscal year (as a percent)		7.13%

[1] See Note 10 for further information regarding fair value measurement inputs and methods.

[2] See Note 10 for further information on fair value measurement inputs and methods.