Employee Benefit Plans - MEC - Defined Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension | MEC
Defined Benefit Plan Disclosure [Line Items]
Settlement gain (loss)	$ 3	$ (4)
Curtailment gain	10
Other Postretirement
Defined Benefit Plan Disclosure [Line Items]
Settlement gain (loss)	0	0	$ 0
Curtailment gain	0	0	0
Other Postretirement | MEC
Defined Benefit Plan Disclosure [Line Items]
Settlement gain (loss)	0	0	0
Curtailment gain	$ 0	$ 0	$ 0