Condensed Financial Information of Registrant - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ (131,918)	$ (14,271)	$ (40,560)	$ (222,337)	$ 35,439	$ (83,891)	$ 28,169	$ 61,092	$ (409,086)	$ 40,809	$ 39,427
Adjustments to reconcile net income (loss) to cash used in operating activities:
Depreciation, depletion, and amortization									90,036	86,121	52,642
Non-cash interest expense									6,902	9,118	7,127
Change in value of common stock warrants									(4,270)	3,199	(1,801)
Stock-based compensation									7,342	6,437	6,196
Equity in losses (income) of subsidiaries									46,905	89,751	(9,464)
Debt extinguishment and commitment costs									0	11,587	4,224
Net changes in operating assets and liabilities:
Prepaid and other assets									29,465	(24,121)	(5,521)
Accounts payable, other accrued liabilities, and operating lease ROU assets and liabilities									67,193	68,969	19,885
Net cash provided by (used in) operating activities									(37,214)	105,630	90,620
Cash flows from investing activities:
Capital expenditures									(63,522)	(83,920)	(48,439)
Other investing activities									58	864	816
Net cash used in investing activities									(63,464)	(353,229)	(175,821)
Cash flows from financing activities:
Proceeds from sale of common stock, net of offering costs									0	0	19,318
Proceeds from borrowings									250,387	510,906	118,741
Repayments of borrowings									(159,489)	(241,336)	(118,751)
Payment of deferred loan costs									(6,266)	(13,450)	(379)
Exercise of stock options									0	8,171	0
Payments for debt extinguishment and commitment costs									0	(8,087)	(3,390)
Other financing activities, net									(428)	582	(860)
Net cash provided by financing activities									42,559	300,208	41,943
Net increase (decrease) in cash, cash equivalents, and restricted cash									(58,119)	52,609	(43,258)
Cash, cash equivalents, and restricted cash at beginning of period				128,428				75,819	128,428	75,819	119,077
Cash, cash equivalents, and restricted cash at end of period	70,309				128,428				70,309	128,428	75,819
Net cash received (paid) for:
Interest									54,256	58,250	28,186
Taxes									(190)	136	49
Non-cash investing and financing activities:
Accrued capital expenditures									4,686	6,386	6,199
ROU assets obtained in exchange for new finance lease liabilities									3,476	963	1,678
ROU assets obtained in exchange for new operating lease liabilities									22,529	79,382	0
Common stock issued for business combination									0	36,980	0
Common stock issued to repurchase convertible notes									0	74,290	0
Parent Company
Cash flows from operating activities:
Net income (loss)									(409,086)	40,809	39,427
Adjustments to reconcile net income (loss) to cash used in operating activities:
Depreciation, depletion, and amortization									2,900	2,969	4,092
Non-cash interest expense									2,518	4,600	4,925
Change in value of common stock warrants									(4,270)	3,199	(1,801)
Stock-based compensation									7,342	6,437	6,196
Equity in losses (income) of subsidiaries									394,197	(81,097)	(81,942)
Debt extinguishment and commitment costs									0	6,091	0
Net changes in operating assets and liabilities:
Prepaid and other assets									(4,253)	1,592	(2,604)
Accounts payable, other accrued liabilities, and operating lease ROU assets and liabilities									(187)	(8,441)	5,601
Net cash provided by (used in) operating activities									(10,839)	(23,841)	(26,106)
Cash flows from investing activities:
Investments in subsidiaries									0	0	0
Distributions from subsidiaries									4,113	16,673	0
Capital expenditures									(1,296)	(1,829)	(3,682)
Due to (from) subsidiaries									5,768	(6,519)	(25,102)
Other investing activities									14	31	0
Net cash used in investing activities									8,599	8,356	(28,784)
Cash flows from financing activities:
Proceeds from sale of common stock, net of offering costs									0	0	19,318
Proceeds from borrowings									14,437	63,406	10,770
Repayments of borrowings									(18,603)	(76,323)	(11,253)
Payment of deferred loan costs									0	(252)	0
Exercise of stock options									0	8,171	0
Payments for debt extinguishment and commitment costs									0	(1,899)	0
Other financing activities, net									164	(10)	(860)
Net cash provided by financing activities									(4,002)	(6,907)	17,975
Net increase (decrease) in cash, cash equivalents, and restricted cash									(6,242)	(22,392)	(36,915)
Cash, cash equivalents, and restricted cash at beginning of period				$ 7,052				$ 29,444	7,052	29,444	66,359
Cash, cash equivalents, and restricted cash at end of period	$ 810				$ 7,052				810	7,052	29,444
Net cash received (paid) for:
Interest									(2,475)	(5,357)	(5,750)
Taxes									(28)	(220)	(49)
Non-cash investing and financing activities:
Accrued capital expenditures									233	497	714
ROU assets obtained in exchange for new finance lease liabilities									173	198	539
ROU assets obtained in exchange for new operating lease liabilities									0	134	0
Common stock issued for business combination									0	36,980	0
Non-cash contribution to subsidiary for business combination									0	(36,980)	0
Common stock issued to repurchase convertible notes									$ 0	$ 74,290	$ 0