Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Property and Equipment Including Oil and Natural Gas Properties

A summary of property and equipment including oil and natural gas properties is as follows (in thousands):

	December 31, 2017			December 31, 2016
Oil and natural gas properties:
Unproved	$	459,549		$	526,270
Proved		1,896,081			1,545,860
Gross oil and natural gas properties		2,355,630			2,072,130
Less accumulated depreciation, depletion and amortization		(1,248,200	)		(1,131,378	)
Oil and natural gas properties, net		1,107,430			940,752
Other property and equipment		13,508			11,447
Less accumulated depreciation		(6,566	)		(4,699	)
Other property and equipment, net		6,942			6,748
Property and equipment, net	$	1,114,372		$	947,500

Summary of Accrued Liabilities

A summary of accrued liabilities is as follows (in thousands):

	December 31, 2017		December 31, 2016
Ad valorem and production taxes	$	4,299	$	4,519
Employee compensation		8,667		4,257
Royalties		9,660		8,557
Short term derivatives		14,876		35,409
Other		4,160		2,302
Total accrued liabilities	$	41,662	$	55,044

Changes in Company's Asset Retirement Obligation Liability

The following table sets forth the changes in the Company’s ARO liability for the period indicated (in thousands):

	Year Ended
	December 31, 2017		December 31, 2016		December 31, 2015
Asset retirement obligations, beginning of period	$	4,806	$	3,401	$	17,400
Liabilities associated with assets held for sale		—		—		(19,057	)
Revisions of prior estimates		—		—		2,913
Additional liabilities incurred		679		1,014		522
Accretion		544		391		1,623
Asset retirement obligations, end of period	$	6,029	$	4,806	$	3,401

Summary of Reconciliation of Amounts in Previously Reported Consolidated Financial Statements

A reconciliation of the effects of the revision to amounts in the previously reported consolidated financial statements is as follows (in thousands, except per share amounts):

	As of  December 31, 2016
	As Reported			Adjustment			As Adjusted
Balance Sheet
Accounts receivable	$	43,638		$	785		$	44,423
Total current assets		249,630			785			250,415
Total assets		1,197,859			785			1,198,644
Accrued liabilities		64,150			(9,106	)		55,044
Total current liabilities		140,625			(9,106	)		131,519
Total liabilities		651,143			(9,106	)		642,037
Accumulated deficit		(1,414,561	)		9,891			(1,404,670	)
Total stockholders' equity		546,716			9,891			556,607
Total liabilities and stockholders' equity		1,197,859			785			1,198,644

	As of  December 31, 2016
	As Reported			Adjustment		As Adjusted
Statement of Stockholders' Equity
Accumulated deficit	$	(1,414,561	)	$	9,891	$	(1,404,670	)
Total stockholders' equity		546,716			9,891		556,607

	As of  December 31, 2015
	As Reported			Adjustment			As Adjusted
Balance Sheet
Accounts receivable	$	27,476		$	253		$	27,729
Total current assets		269,384			253			269,637
Total assets		1,266,412			253			1,266,665
Accounts payable		34,717			2,137			36,854
Accrued liabilities		25,462			(14,704	)		10,758
Total current liabilities		113,842			(12,567	)		101,275
Total liabilities		645,858			(12,567	)		633,291
Accumulated deficit		(1,210,755	)		12,820			(1,197,935	)
Total stockholders' equity		620,554			12,820			633,374
Total liabilities and stockholders' equity		1,266,412			253			1,266,665

	As of  December 31, 2015
	As Reported			Adjustment		As Adjusted
Statement of Stockholders' Equity
Accumulated deficit	$	(1,210,755	)	$	12,820	$	(1,197,935	)
Total stockholders' equity		620,554			12,820		633,374

	As of  December 31, 2014
	As Reported			Adjustment		As Adjusted
Statement of Stockholders' Equity
Accumulated deficit	$	(239,345	)	$	3,201	$	(236,144	)
Total stockholders' equity		1,152,711			3,201		1,155,912

	As of  December 31, 2016
	As Reported			Adjustment			As Adjusted
Statement of Operations
Production and ad valorem taxes	$	4,998		$	2,929		$	7,927
Total operating expenses		349,507			2,929			352,436
Operating loss		(114,473	)		(2,929	)		(117,402	)
Loss before income taxes		(203,260	)		(2,929	)		(206,189	)
Net loss		(203,806	)		(2,929	)		(206,735	)
Basic and diluted loss per share	$	(0.84	)	$	(0.02	)	$	(0.86	)

	As of  December 31, 2015
	As Reported			Adjustment			As Adjusted
Statement of Operations
Production and ad valorem taxes	$	11,621		$	(7,899	)	$	3,722
Total operating expenses		1,242,806			(7,899	)		1,234,907
Operating loss		(987,485	)		7,899			(979,586	)
Loss before income taxes		(1,043,856	)		7,899			(1,035,957	)
Income tax benefit (expense)		72,446			1,720			74,166
Net loss		(971,410	)		9,619			(961,791	)
Basic and diluted loss per share	$	(4.46	)	$	0.05		$	(4.41	)

	As of  December 31, 2016
	As Reported			Adjustment			As Adjusted
Statement of Comprehensive Loss
Net loss	$	(203,806	)	$	(2,929	)	$	(206,735	)
Total Comprehensive loss		(203,806	)		(2,929	)		(206,735	)

	As of  December 31, 2015
	As Reported			Adjustment		As Adjusted
Statement of Comprehensive Loss
Net loss	$	(971,410	)	$	9,619	$	(961,791	)
Total Comprehensive loss		(970,862	)		9,619		(961,243	)

	As of December 31, 2016
	As Reported			Adjustment			As Adjusted
Statement of Cash Flows
Net loss	$	(203,806	)	$	(2,929	)	$	(206,735	)
Accounts receivable		(20,563	)		(714	)		(21,277	)
Accounts payable and accrued liabilities		(2,849	)		3,643			794

	As of December 31, 2015
	As Reported			Adjustment			As Adjusted
Statement of Cash Flows
Net loss	$	(971,410	)	$	9,619		$	(961,791	)
Deferred income taxes		(72,761	)		(1,720	)		(74,481	)
Accounts receivable		20,437			(228	)		20,209
Accounts payable and accrued liabilities		24,721			(7,671	)		17,050

Sales Revenue, Services, Net [Member] | Customer Concentration Risk [Member]

Concentration Risk

The following table sets forth the Company’s major customers and associated percentage of revenue for the periods indicated:

	For the Year Ended December 31,
	2017			2016			2015
Purchaser
Antero Resources Corporation		—			14	%		19	%
ARM Energy Management		—			—			11	%
Concord Energy, LLC		—			12	%		—
Emera Energy Services		17	%		—			—
EnLink Midstream Operating		—			17	%		21	%
Marathon Petroleum		10	%		—			—
Sequent Energy Management		—			20	%		19	%
Total		27	%		63	%		70	%

Accounts Receivable [Member] | Product Concentration Risk [Member]

Concentration Risk

The following table summarizes concentration of receivables, net of allowances, by product or service as of December 31, 2017 and December 31, 2016 (in thousands):

	December 31, 2017		December 31, 2016
Receivables by product or service:
Sale of oil and natural gas and related products    and services	$	52,908	$	41,398
Joint interest owners		23,154		2,850
Derivatives		1,528		122
Other		19		53
Total	$	77,609	$	44,423