Debt and Financing Arrangements (Details) $ in Thousands							3 Months Ended
	Feb. 16, 2024 shares	Feb. 08, 2024 USD ($)	Aug. 03, 2022 USD ($)	Jul. 29, 2021 USD ($) M	Nov. 03, 2020 USD ($)	Jul. 02, 2020 USD ($)	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Aug. 02, 2022 USD ($)	Mar. 04, 2021 USD ($)
Debt Instrument [Line Items]
Payments on term loan							$ 3,502	$ 750
Receipt of shares from the exercise of capped call | shares	315,721						315,721
Proceeds from issuance of debt							$ 20,000
Restricted cash							1,100	$ 1,100	$ 1,100
Debt financing costs		$ 1,500					1,500
Outstanding debt							143,300		$ 140,595
New Term Loan Debt Facility | Secured Debt
Debt Instrument [Line Items]
Term loan, face value		20,000
Amortization payments		$ 3,300
Term loan due 2025
Debt Instrument [Line Items]
Term loan, face value							20,000
Total net leverage		2.00
Term of financial maintenance covenants, maximum total net leverage ratio		12 months
Maximum consolidated EBITDA to consolidated interest expense ratio		3.50
Term of financial maintenance covenants on consolidated EBITDA		12 months
Customary mandatory prepayment events		100.00%
Term loan due 2025 | Minimum
Debt Instrument [Line Items]
Financial maintenance covenant for liquidity		$ 100,000
Term loan due 2025 | SOFR
Debt Instrument [Line Items]
Applicable margin on interest rate		3.00%
Adjustment to basis spread on variable rate		10.00%
Floor, basis spread on variable rate		0.00%
Term loan due 2025 | Base Rate
Debt Instrument [Line Items]
Applicable margin on interest rate		2.00%
Term loan due 2024
Debt Instrument [Line Items]
Payments on term loan		$ 3,500
Accounts Receivable Securitization Facility | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Current borrowing capacity							98,100
Letters of credit outstanding							51,900
Accounts Receivable Securitization Facility | Regions Bank | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Current borrowing capacity			$ 150,000							$ 110,000
Inventory-Based Revolving Credit Facility
Debt Instrument [Line Items]
Covenant amount							23,800
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Term loan, face value			$ 50,000
Letters of credit outstanding							26,200
Borrowing base percentage, coal inventory			85
Borrowing base percentage, parts and supplies inventory			85
Borrowing base, percentage of clause			35
Percent of eligible cash			100.00%
Covenant amount			$ 100,000
Equipment financing arrangement | Secured Debt
Debt Instrument [Line Items]
Term loan, face value				$ 23,500
Number of monthly payments | M				42
Interest rate				7.35%
Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value							98,100
Series 2020 Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value						$ 53,100
Interest rate						5.00%
Mandatory tender percentage						100.00%
Series 2021 Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value											$ 45,000
Interest rate											4.125%
Convertible Notes
Debt Instrument [Line Items]
Term loan, face value					$ 155,300
Interest rate					5.25%
Net proceeds of convertible debt					$ 132,700
Principal amount of convertible notes							13,200
Cash on convertible notes							58,400
Deferred Offering Costs					5,100
Loss on debt conversion							$ 1,100
Capped Call Transactions
Debt Instrument [Line Items]
Capped call, transaction cost					$ 17,500