Pension and Other Postretirement Employee Benefit Plans - Gains and Losses (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Decrease in plan assets as a result of settlement and remeasurement of the plan		$ 4.0
Decrease in benefit obligation as a result of settlement and remeasurement of the plan		2.6
Decrease in accumulated other comprehensive income as a result of settlement and remeasurement of the plan		$ 1.4
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Percent above which amortization of net gains and losses is included in annual net periodic benefit cost	10.00%