Pensions and Other Postretirement Benefits (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2025	Dec. 31, 2025
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost	$ 8	$ 7
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost	5	5
Mandatory Contribution
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to defined benefit pension plans	$ 0	$ 1
Scenario, Forecast | Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost				$ 35
Scenario, Forecast | Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost				$ 20
Scenario, Forecast | Mandatory Contribution | Pension | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to defined benefit pension plans			$ 20
Scenario, Forecast | Mandatory Contribution | Pension | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to defined benefit pension plans			$ 30