Debt and Financing Arrangements (Details) $ / shares in Units, shares in Millions										9 Months Ended	12 Months Ended
	Aug. 03, 2022 USD ($)	Jul. 29, 2021 USD ($) installment	Nov. 03, 2020 USD ($) $ / shares	Nov. 02, 2020 $ / shares	Nov. 01, 2020 shares	Oct. 29, 2020 USD ($) $ / shares	Jul. 02, 2020 USD ($)	Mar. 04, 2020 USD ($) installment	Mar. 07, 2017 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2018	Aug. 02, 2022 USD ($)	Mar. 04, 2021 USD ($)	Nov. 30, 2020 USD ($)
Debt Instrument [Line Items]
Term loan, face value																	$ 155,300,000
Interest rate																	5.25%
Restricted cash											$ 1,100,000	$ 1,101,000	$ 5,953,000
Net proceeds of convertible debt													155,250,000
Debt financing costs											1,035,000	2,057,000	$ 9,718,000
Unamortized deferred financing fees											1,600,000	1,200,000
Outstanding debt											174,276,000	560,673,000
Derivative Assets											2,707,000	6,104,000
Paid-in Capital
Debt Instrument [Line Items]
Cash on convertible notes																	$ 39,200,000
Retained Earnings
Debt Instrument [Line Items]
Cash on convertible notes																	$ 6,700,000
New Term Loan Debt Facility | Senior Notes
Debt Instrument [Line Items]
Term loan, face value									$ 300,000,000
Percentage of face amount									99.50
Term loan repaid											273,800,000
Amount of voting equity interests of domestic subsidiaries guaranteed (percent)									100
Amount of voting equity interests of foreign owned subsidiaries guaranteed (percent)									65
Outstanding debt											6,500,000
Loss on Early Repayment of Debt											4,100,000
New Term Loan Debt Facility | Line of Credit | LIBOR
Debt Instrument [Line Items]
Applicable margin on interest rate														2.75%
New Term Loan Debt Facility | Line of Credit | LIBOR | Minimum
Debt Instrument [Line Items]
Applicable margin on interest rate														1.00%
New Term Loan Debt Facility | Line of Credit | Base Rate
Debt Instrument [Line Items]
Applicable margin on interest rate														1.75%
Interest Rate Swap
Debt Instrument [Line Items]
Amount reclassified from other comprehensive income to expense											1,400,000
Derivative Assets											1,200,000
New Term Loan Debt Facility | Senior Notes
Debt Instrument [Line Items]
Quarterly principal amortization payments									$ 800,000
Mandatory prepayment amount (as percent)									100
Default to indebtedness									$ 50,000,000
Default to surety, reclamation, or similar bonds securing obligations									50,000,000
Default to uninsured judgment									50,000,000
Uninsured losses or proceedings against minimum amount									$ 50,000,000
Accounts Receivable Securitization Facility | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Current borrowing capacity											101,400,000
Letters of credit outstanding											48,600,000
Accounts Receivable Securitization Facility | Regions Bank | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Current borrowing capacity	$ 150,000,000														$ 110,000,000
Inventory-Based Revolving Credit Facility
Debt Instrument [Line Items]
Covenant amount											23,800,000
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Term loan, face value	$ 50
Letters of credit outstanding											$ 26,200,000
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	$ 100,000,000									$ 100,000,000
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt | LIBOR
Debt Instrument [Line Items]
Applicable margin on interest rate											0.75%
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt | LIBOR | Minimum
Debt Instrument [Line Items]
Applicable margin on interest rate											2.50%
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt | LIBOR | Maximum
Debt Instrument [Line Items]
Applicable margin on interest rate											3.50%
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt | Base Rate | Minimum
Debt Instrument [Line Items]
Applicable margin on interest rate											1.50%
Inventory-Based Revolving Credit Facility | Regions Bank | Line of Credit | Secured Debt | Base Rate | Maximum
Debt Instrument [Line Items]
Applicable margin on interest rate											2.50%
Equipment financing arrangement | Secured Debt
Debt Instrument [Line Items]
Term loan, face value		$ 23,500,000						$ 53,600,000
Number of monthly payments | installment		42						48
Interest rate		7.35%						6.34%
Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value											$ 98,100,000
Tax Exempt Bonds | Minimum
Debt Instrument [Line Items]
Covenant for cross-events of default to indebtedness										$ 50,000,000
Series 2020 Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value							$ 53,100,000
Interest rate							5.00%
Mandatory tender percentage							100.00%
Series 2021 Tax Exempt Bonds
Debt Instrument [Line Items]
Term loan, face value																$ 45,000,000.0
Interest rate																4.125%
Convertible Notes
Debt Instrument [Line Items]
Term loan, face value			$ 155,300,000
Interest rate			5.25%
Net proceeds of convertible debt			$ 132,700,000
Initial Conversion ratio			26.7917
Initial Conversion price (in dollars per share) | $ / shares			$ 37.325								$ 31.751
Stock price trigger (as a percent)			130.00%
Trading days, number			20
Convertible Notes exceeded the principal amount											$ 46,000,000.0
Consecutive trading days, period			30
Total interest expense											4,700,000	15,100,000
Contractual interest coupon											4,100,000	8,200,000
Amortization of debt discount											600,000	$ 6,900,000
Principal amount of convertible notes											142,100,000
Cash on convertible notes											208,100,000
Deferred Offering Costs			$ 5,100,000
Outstanding debt											13,200,000
Unamortized Debt Issuance Expense											$ 3,800,000
Debt conversion, number of shares | shares											2.6
Loss on debt conversion											$ 10,300,000
Inducement premium payment											5,000,000.0
Professional fees											1,500,000
Capped Call Transactions
Debt Instrument [Line Items]
Initial strike price (in dollars per share) | $ / shares			$ 37.325
Number of underlying shares | shares					4.2
Cap price | $ / shares				$ 52.255		$ 52.2550
Premium percentage (as percent)						75.00%
Capped call, transaction cost			$ 17,500,000			$ 17,500,000
Debt instrument capped call transaction intrinsic value											$ 62,100,000