Long-Term Debt - Narrative (Details) - USD ($)			1 Months Ended	3 Months Ended
	Mar. 27, 2025	Jan. 13, 2025	Jan. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Segment assets				$ 6,055,921,000	$ 6,251,946,000	$ 6,130,053,000
Net Income (Loss)				21,044,000	(69,277,000)
Loss on extinguishment of debt				0	11,680,000
Arch Resources, Inc
Debt Instrument [Line Items]
Purchase price consideration		$ 98,075,000
Accounts Receivable Securitization Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 250,000,000
Reduced annual rate				0.10%
Letters of credit outstanding				$ 158,282,000		158,282,000
Available borrowing capacity				33,039,000		$ 26,840,000
Proceeds from Lines of Credit				0	0
Repayments of Lines of Credit				$ 0	0
PEDFA Solid Waste Disposal Facility Revenue Bonds at 5.45%
Debt Instrument [Line Items]
Letters of credit outstanding	$ 75,000,000
Debt instrument, face amount	$ 97,560,000
Debt instrument, interest rate, stated percentage	5.45%			5.45%		5.45%
Debt instrument, term	10 years
MEDCO Port Facilities Refunding Revenue Bonds at 5.00%
Debt Instrument [Line Items]
Letters of credit outstanding	$ 102,865,000
Debt instrument, face amount	$ 102,865,000
Debt instrument, interest rate, stated percentage	5.00%			5.00%		5.00%
Debt instrument, term	10 years
WVEDA Solid Waste Disposal Facility Revenue Bonds at 5.45%
Debt Instrument [Line Items]
Debt instrument, face amount	$ 106,355,000
Debt instrument, interest rate, stated percentage	5.45%			5.45%		5.45%
Debt instrument, term	10 years
Non-Guarantor Subsidiaries
Debt Instrument [Line Items]
Segment assets				$ 368,973,000		$ 350,156,000
Trade receivables				366,100,000		347,093,000
Net Income (Loss)				957,000	$ 2,898,000
Revolving Credit Facility
Debt Instrument [Line Items]
Borrowings outstanding				$ 0		0
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 600,000,000				$ 355,000,000
Period for outstanding amounts prior to stated maturity			91 days
Liquidity requirement			$ 250,000,000
Reduced annual rate			0.75%	0.10%
Letters of credit outstanding				$ 110,351,000		110,098,000
Available borrowing capacity				$ 489,649,000		$ 489,902,000
Revolving Credit Facility and TLA Facility | Line of Credit
Debt Instrument [Line Items]
Debt instrument, covenant, net leverage ratio, maximum				2.50
Debt instrument, covenant, fixed charge coverage ratio, minimum				3.00
Debt instrument, covenant, first lien gross leverage ratio, actual				0.25
Debt instrument, covenant, net leverage ratio, actual				0.07
Debt instrument, covenant, fixed charge coverage ratio, actual				31.61
Revolving Credit Facility and TLA Facility | Line of Credit | Maximum
Debt Instrument [Line Items]
Debt instrument, covenant, first lien gross leverage ratio				1.50
Series 2020 | WVEDA Solid Waste Disposal Facility Revenue Bonds at 5.45%
Debt Instrument [Line Items]
Letters of credit outstanding	$ 53,090,000
Series 2021 | WVEDA Solid Waste Disposal Facility Revenue Bonds at 5.45%
Debt Instrument [Line Items]
Letters of credit outstanding	$ 44,985,000