Debt and Financing Arrangements (Details) $ / shares in Units, shares in Millions							6 Months Ended	12 Months Ended
	Aug. 03, 2022 USD ($)	Jul. 29, 2021 USD ($) installment	Nov. 03, 2020 USD ($) $ / shares shares	Oct. 29, 2020 $ / shares	Jul. 02, 2020 USD ($)	Mar. 04, 2020 USD ($) installment	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2017 USD ($)	Aug. 02, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 04, 2021 USD ($)
Debt Instrument [Line Items]
Restricted cash							$ 1,100,000	$ 1,100,000			$ 1,100,000
Outstanding debt							135,630,000	174,276,000
Derivative Assets							230,000	2,707,000
New Term Loan Debt Facility | Senior Notes
Debt Instrument [Line Items]
Term loan, face value									$ 300,000,000
Percentage of face amount									99.50
Quarterly principal amortization payments									$ 750,000
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							5,000,000.0
New Term Loan Debt Facility | Line of Credit | London Interbank Market Rate [Member]
Debt Instrument [Line Items]
Applicable margin on interest rate									2.75%
New Term Loan Debt Facility | Line of Credit | London Interbank Market Rate [Member] | 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%
Accounts Receivable Securitization Facility | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Current borrowing capacity							101,800,000
Letters of credit outstanding							48,200,000
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	$ 50,000,000
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
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
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
Principal amount of convertible notes							13,200,000
Cash on convertible notes							58,400,000
Deferred Offering Costs			$ 5,100,000
Loss on debt conversion							1,100,000
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
Capped call, transaction cost			$ 17,500,000
Debt instrument capped call transaction intrinsic value							$ 62,100,000