CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net Income	$ 40,809,000	$ 39,427,000	$ 72,621,000
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, depletion, and amortization	86,121,000	52,642,000	45,989,000
Debt extinguishment and commitment costs	11,587,000	4,224,000	8,633,000
Non-cash interest expense	9,118,000	7,127,000	7,276,000
Change in value of common stock warrants	3,199,000	(1,801,000)	1,674,000
Deferred taxes	(66,886,000)	661,000	(1,321,000)
Stock-based compensation	6,437,000	6,196,000	7,204,000
Unrealized (gain) loss on derivative contracts	9,350,000	2,122,000	(989,000)
Equity (earnings) losses from Laramie Energy, LLC	89,751,000	(9,464,000)	(18,369,000)
Net changes in operating assets and liabilities:
Trade accounts receivable	(36,652,000)	(35,790,000)	(19,100,000)
Collateral posted with broker for derivative transactions	(8,797,000)	(3,790,000)	2,499,000
Prepaid and other assets	(24,121,000)	(5,521,000)	37,645,000
Inventories	(195,440,000)	31,840,000	(146,533,000)
Deferred turnaround expenditures	(9,800,000)	0	0
Obligations under inventory financing agreements	121,985,000	(17,138,000)	143,034,000
Accounts payable, other accrued liabilities, and operating lease assets and liabilities	68,969,000	19,885,000	(33,780,000)
Net cash provided by operating activities	105,630,000	90,620,000	106,483,000
Cash flows from investing activities:
Acquisitions, net of cash acquired	(273,399,000)	(74,331,000)	0
Proceeds (expenditures) related to asset acquisition	3,226,000	(53,867,000)	0
Capital expenditures	(83,920,000)	(48,439,000)	(31,708,000)
Other investing activities	864,000	816,000	35,000
Net cash used in investing activities	(353,229,000)	(175,821,000)	(31,673,000)
Cash flows from financing activities:
Proceeds from sale of common stock, net of offering costs	0	19,318,000	0
Proceeds from borrowings	510,906,000	118,741,000	616,706,000
Repayments of borrowings	(241,336,000)	(118,751,000)	(603,770,000)
Net borrowings (repayments) on deferred payment arrangements and receivable advances	43,422,000	27,264,000	(2,198,000)
Payment of deferred loan costs	(13,450,000)	(379,000)	(10,064,000)
Exercise of stock options	8,171,000	0	0
Payments for debt extinguishment and commitment costs	(8,087,000)	(3,390,000)	(4,432,000)
Other financing activities, net	582,000	(860,000)	(993,000)
Net cash provided by (used in) financing activities	300,208,000	41,943,000	(4,751,000)
Net increase (decrease) in cash, cash equivalents, and restricted cash	52,609,000	(43,258,000)	70,059,000
Cash, cash equivalents, and restricted cash at beginning of period	75,819,000	119,077,000	49,018,000
Cash, cash equivalents, and restricted cash at end of period	128,428,000	75,819,000	119,077,000
Net cash received (paid) for:
Interest	(58,250,000)	(28,186,000)	(23,873,000)
Taxes	(136,000)	(49,000)	(1,478,000)
Non-cash investing and financing activities:
Accrued capital expenditures	6,386,000	6,199,000	2,926,000
ROU assets obtained in exchange for new finance lease liabilities	963,000
ROU assets obtained in exchange for new finance lease liabilities		1,678,000	165,000
ROU assets obtained in exchange for new operating lease liabilities	79,382,000
Common stock issued for business combination	36,980,000	0	0
Common stock issued to repurchase convertible notes	$ 74,290,000	$ 0	$ 0