Segment Information - Revenue from External Customers (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026 USD ($) customer	Jun. 30, 2025 USD ($) customer	Jun. 30, 2026 USD ($) customer	Jun. 30, 2025 USD ($) customer
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Revenues	$ 491,505	$ 548,675	$ 1,015,038	$ 1,078,342
Total revenues	$ 492,856	$ 550,274	$ 1,017,843	$ 1,082,231
Revenues \| Customer Concentration Risk
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Number of customers exceeding 10% of total trade accounts receivable, net \| customer	2	3	3	4
Revenues \| Customer Concentration Risk \| Top Customer
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Concentration risk (as a percent)	15.00%	16.00%	13.00%	14.00%
Revenues \| Customer Concentration Risk \| Top 10 Customers
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Concentration risk (as a percent)	73.00%	80.00%	76.00%	80.00%
Accounts Receivable \| Customer Concentration Risk
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Number of customers exceeding 10% of total trade accounts receivable, net \| customer			3	3
Export Coal Revenue
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Revenues	$ 353,683	$ 394,979	$ 757,104	$ 790,694
Export Coal Revenue \| Revenues \| Geographic Concentration Risk
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Concentration risk (as a percent)	72.00%	72.00%	75.00%	73.00%

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