Postretirement Benefit Obligations - Narrative (Details) $ in Millions	1 Months Ended
Mar. 31, 2024 USD ($)
Postemployment Benefits [Abstract]
Excess assets from PA Mines UMWA Plan VEBA	$ 10
Gain on transfer of excess assets	$ 10

Amount of increase (decrease) in plan assets of defined benefit plan from assets transferred into (from) plan.

No definition available.

Name:	us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration