Condended Financial Information of Registrant Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 75,076	$ 118,333
Restricted cash	743	744
Total cash, cash equivalents, and restricted cash	75,819	119,077	$ 49,018	$ 168,536
Prepaid and other current assets	28,370	17,279
Total current assets	586,592	603,544
Property and equipment
Total property and equipment	649,768	529,638
Less accumulated depreciation and depletion	(111,507)	(79,622)
Property, plant, and equipment, net	538,261	450,016
Long-term assets
Other long-term assets	21,881	32,864
Total assets	1,460,734	1,347,407	1,145,433
Current liabilities
Accounts payable	54,787	52,543
Other accrued liabilities	54,562	27,444
Total current liabilities	507,201	470,952
Long-term liabilities
Long-term debt, net of current maturities	392,607	384,812
Common stock warrants	5,007	6,808
Long-term capital lease obligations	6,123	1,220
Other liabilities	37,467	35,896
Total liabilities	948,405	899,688
Stockholders’ equity
Preferred stock, $0.01 par value: 3,000,000 shares authorized, none issued	0	0
Common stock, $0.01 par value; 500,000,000 shares authorized at December 31, 2018 and December 31, 2017, 46,983,924 shares and 45,776,087 shares issued at December 31, 2018 and December 31, 2017, respectively	470	458
Additional paid-in capital	617,937	593,295
Accumulated deficit	(108,751)	(148,178)
Accumulated other comprehensive income	2,673	2,144
Total stockholders’ equity	512,329	447,719
Total liabilities and stockholders’ equity	1,460,734	1,347,407
Parent Company
Current assets
Cash and cash equivalents	28,701	65,615
Restricted cash	743	744
Total cash, cash equivalents, and restricted cash	29,444	66,359	$ 11,107	$ 91,771
Prepaid and other current assets	11,711	11,768
Due from subsidiaries	43,928	8,113
Total current assets	85,083	86,240
Property and equipment
Total property and equipment	18,939	15,773
Less accumulated depreciation and depletion	(9,034)	(6,226)
Property, plant, and equipment, net	9,905	9,547
Long-term assets
Investment in subsidiaries	638,975	552,748
Other long-term assets	3,334	1,976
Total assets	737,297	650,511
Current liabilities
Accounts payable	8,312	4,510
Other accrued liabilities	12,349	12,913
Due to subsidiaries	96,963	82,524
Total current liabilities	117,624	99,947
Long-term liabilities
Long-term debt, net of current maturities	100,411	95,486
Common stock warrants	5,007	6,808
Long-term capital lease obligations	475	551
Other liabilities	1,451	0
Total liabilities	224,968	202,792
Stockholders’ equity
Preferred stock, $0.01 par value: 3,000,000 shares authorized, none issued	0	0
Common stock, $0.01 par value; 500,000,000 shares authorized at December 31, 2018 and December 31, 2017, 46,983,924 shares and 45,776,087 shares issued at December 31, 2018 and December 31, 2017, respectively	470	458
Additional paid-in capital	617,937	593,295
Accumulated deficit	(108,751)	(148,178)
Accumulated other comprehensive income	2,673	2,144
Total stockholders’ equity	512,329	447,719
Total liabilities and stockholders’ equity	$ 737,297	$ 650,511