Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net income	$ 23,046	$ 21,681
Adjustments to reconcile net income to net cash from operating activities:
Accretion of asset retirement obligations	383	370
Depreciation and amortization	14,291	8,741
Amortization of debt issuance costs	43	406
Stock-based compensation.	3,058	1,940
Deferred income tax expense	4,561	1,448
Changes in operating assets and liabilities
Accounts receivable	(19,325)	(24,122)
Prepaid expenses and other current assets	(170)	(942)
Inventories	1,541	2,107
Advance coal royalties	(205)	(172)
Other assets and liabilities	634	(307)
Accounts payable	(5,291)	5,236
Accrued expenses	3,062	4,087
Net cash from operating activities	25,628	20,473
Cash flow from investing activities
Purchases of property, plant and equipment	(34,043)	(39,883)
Proceeds from maturities of investment securities		5,200
Net cash from investing activities	(34,043)	(34,683)
Cash flows from financing activities
Proceeds from borrowings	58,050	13,000
Proceeds from notes payable - related party		3,000
Payment of debt issuance costs		(569)
Repayments of borrowings	(50,801)	(1,000)
Repayments of financed insurance payable	(287)	(673)
Net cash from financing activities	6,962	13,758
Net change in cash and cash equivalents	(1,453)	(452)
Cash and cash equivalents, beginning of period	6,951	5,934
Cash and cash equivalents, end of period	5,498	5,482
Supplemental cash flow information
Cash paid for interest	821	801
Non-cash investing and financing activities
Capital expenditures included in accounts payable and accrued expenses	4,068	894
Financed insurance		1,276
Additional asset retirement obligations incurred	$ 239	$ 200