Accumulated Other Comprehensive Loss - Schedule of Changes to Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,649,497	$ 1,573,928
Ending balance	1,613,710	1,643,570
Employee benefit costs
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(50,082)	(40,587)
Other comprehensive loss before reclassifications	(1,312)	(9,442)
Amounts reclassified from accumulated other comprehensive loss	2,207	1,709
Ending balance	$ (49,187)	$ (48,320)

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Alpha Metallurgical Resources, Inc. 10-Q