Employee Benefits - Overview of the accumulated benefit obligation, fair value of plan assets, funded status and net amount (Details) - Other Post-Retirement Benefits - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated projected benefit obligation	$ 91	$ 83
Fair value of plan assets	15	14
Funded status	(76)	(69)
Unrecognized prior-service credit	0	(1)
Unrecognized loss	(16)	(19)
Net amount recognized	$ (92)	$ (89)

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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