CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ (409,086,000)	$ 40,809,000	$ 39,427,000
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Depreciation, depletion, and amortization	90,036,000	86,121,000	52,642,000
Asset impairment loss	85,806,000	0	0
Debt extinguishment and commitment costs	0	11,587,000	4,224,000
Non-cash interest expense	6,902,000	9,118,000	7,127,000
Non-cash lower of cost and net realizable value adjustment	10,595,000	(3,752,000)	3,752,000
Change in value of common stock warrants	(4,270,000)	3,199,000	(1,801,000)
Deferred taxes	(20,895,000)	(66,886,000)	661,000
Stock-based compensation	7,342,000	6,437,000	6,196,000
Unrealized (gain) loss on derivative contracts	(3,322,000)	9,350,000	2,122,000
Equity (earnings) losses from Laramie Energy, LLC	46,905,000	89,751,000	(9,464,000)
Net changes in operating assets and liabilities:
Trade accounts receivable	117,801,000	(36,652,000)	(35,790,000)
Collateral posted with broker for derivative transactions	7,035,000	(8,797,000)	(3,790,000)
Prepaid and other assets	29,465,000	(24,121,000)	(5,521,000)
Inventories	171,880,000	(191,688,000)	28,088,000
Deferred turnaround expenditures	(49,770,000)	(9,800,000)	0
Obligations under inventory financing agreements	(190,831,000)	121,985,000	(17,138,000)
Accounts payable, other accrued liabilities, and operating lease ROU assets and liabilities	67,193,000	68,969,000	19,885,000
Net cash provided by (used in) operating activities	(37,214,000)	105,630,000	90,620,000
Cash flows from investing activities:
Acquisitions, net of cash acquired	0	(273,399,000)	(74,331,000)
Proceeds (expenditures) related to asset acquisition	0	3,226,000	(53,867,000)
Capital expenditures	(63,522,000)	(83,920,000)	(48,439,000)
Other investing activities	58,000	864,000	816,000
Net cash used in investing activities	(63,464,000)	(353,229,000)	(175,821,000)
Cash flows from financing activities:
Proceeds from sale of common stock, net of offering costs	0	0	19,318,000
Proceeds from borrowings	250,387,000	510,906,000	118,741,000
Repayments of borrowings	(159,489,000)	(241,336,000)	(118,751,000)
Net borrowings (repayments) on deferred payment arrangements and receivable advances	(41,645,000)	43,422,000	27,264,000
Payment of deferred loan costs	(6,266,000)	(13,450,000)	(379,000)
Exercise of stock options	0	8,171,000	0
Payments for debt extinguishment and commitment costs	0	(8,087,000)	(3,390,000)
Other financing activities, net	(428,000)	582,000	(860,000)
Net cash provided by financing activities	42,559,000	300,208,000	41,943,000
Net increase (decrease) in cash, cash equivalents, and restricted cash	(58,119,000)	52,609,000	(43,258,000)
Cash, cash equivalents, and restricted cash at beginning of period	128,428,000	75,819,000	119,077,000
Cash, cash equivalents, and restricted cash at end of period	70,309,000	128,428,000	75,819,000
Net cash received (paid) for:
Interest	(54,256,000)	(58,250,000)	(28,186,000)
Taxes	190,000	(136,000)	(49,000)
Non-cash investing and financing activities:
Accrued capital expenditures	4,686,000	6,386,000	6,199,000
Value of warrants reclassified to equity	3,936,000	0	0
ROU assets obtained in exchange for new finance lease liabilities	3,476,000	963,000	1,678,000
ROU assets obtained in exchange for new operating lease liabilities	22,529,000	79,382,000	0
ROU assets terminated in exchange for release from finance lease liabilities	0	0	0
ROU assets terminated in exchange for release from operating lease liabilities	7,738,000	193,000	0
Common stock issued for business combination	0	36,980,000	0
Common stock issued to repurchase convertible notes	$ 0	$ 74,290,000	$ 0