Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 20, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net income	$ 7,556	$ 25,257	$ 33,280	$ 41,471	$ 32,813	$ 31,382	$ 74,751
Adjustments to reconcile net income to net cash from operating activities:
Accretion of asset retirement obligations	349		755		700		990
Depreciation, depletion, and amortization	13,556		9,783		25,407		18,463
Amortization of debt issuance costs					357		243
Stock-based compensation					6,505		4,173
Other income					(1,936)		(2,113)
Deferred income taxes					6,620		6,448
Changes in operating assets and liabilities:
Accounts receivable					(17,799)		(8,293)
Prepaid expenses and other current assets					5,106		1,472
Inventories					(22,452)		(16,597)
Other assets and liabilities					(957)		1,263
Accounts payable					13,030		10,060
Accrued liabilities					2,184		18,441
Net cash provided by operating activities					49,578		109,301
Cash flow from investing activities:
Capital expenditures					(48,016)		(53,807)
Acquisition of Ramaco Coal assets							(11,738)
Other					3,000		2,000
Net cash used for investing activities					(43,834)		(63,545)
Cash flows from financing activities:
Proceeds from borrowings					77,500		1,337
Payment of dividends					(11,108)		(9,996)
Repayment of borrowings					(42,588)		(9,407)
Repayment of Ramaco Coal acquisition financing - related party					(20,000)
Repayments of insurance financing					(3,001)		(210)
Repayments of equipment finance leases					(3,098)		(2,718)
Shares surrendered for withholding taxes payable					(5,179)		(2,821)
Net cash used for financing activities					(7,474)		(23,815)
Net change in cash and cash equivalents and restricted cash					(1,730)		21,941
Cash and cash equivalents and restricted cash, beginning of period		$ 36,473		$ 22,806	36,473	$ 36,473	22,806
Cash and cash equivalents and restricted cash, end of period	34,743		$ 44,747		34,743		44,747
Non-cash investing and financing activities:
Leased assets obtained under new financing leases					7,874		3,624
Capital expenditures included in accounts payable and accrued liabilities					14,615		15,609
Ramaco Coal acquisition financing							$ 56,551
Financed insurance					406
Tax liability on shares surrendered by employees					144
Accrued dividends payable	$ 504				504
Maben Asset Acquisition
Cash flow from investing activities:
Maben acquisition bond recovery					$ 1,182