GUARANTOR FINANCIAL STATEMENTS - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Jul. 01, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 190,581		$ 10,759	$ 74,488	$ 331,224
Accounts receivable	48,464		48,031
Fair value of derivative contracts	0		38,576
Current income tax receivable	26,086		46,174
Other current assets	10,151		6,881
Total current assets	275,282		150,421
Oil and gas properties, full cost method:
Proved	9,616,236		9,375,898
Less: accumulated DD&A	(9,178,442)		(8,603,955)
Net proved oil and gas properties	437,794		771,943
Unevaluated	373,720		440,043
Other property and equipment, net	26,213		29,289
Other assets, net	26,474		18,473
Investment in subsidiary	0		0
Total assets	1,139,483		1,410,169
Current liabilities:
Accounts payable to vendors	19,981		82,207
Undistributed oil and gas proceeds	15,073		5,992
Accrued interest	809		9,022
Asset retirement obligations	88,000		21,291
Current portion of long-term debt	408		0
Other current liabilities	18,602		40,712
Total current liabilities	142,873		159,224
Long-term debt	352,376		1,060,955
Asset retirement obligations	154,019		204,575
Other long-term liabilities	17,315		25,204
Total liabilities not subject to compromise	666,583		1,449,958
Liabilities subject to compromise	1,110,182		0
Total liabilities	1,776,765		1,449,958
Commitments and contingencies
Stockholders’ equity:
Common stock	56		55
Treasury stock	(860)		(860)
Additional paid-in capital	1,659,731		1,648,687
Accumulated deficit	(2,296,209)		(1,705,623)
Accumulated other comprehensive income	0		17,952
Total stockholders’ equity	(637,282)	$ 50,000	(39,789)
Total liabilities and stockholders’ equity	1,139,483		1,410,169
Eliminations
Current assets:
Cash and cash equivalents	0		0	0	0
Accounts receivable	(1,733)		(1,756)
Fair value of derivative contracts			0
Current income tax receivable	0		0
Other current assets	0		0
Total current assets	(1,733)		(1,756)
Oil and gas properties, full cost method:
Proved	0		0
Less: accumulated DD&A	0		0
Net proved oil and gas properties	0		0
Unevaluated	0		0
Other property and equipment, net	0		0
Other assets, net	0		0
Investment in subsidiary	(389,551)		(746,121)
Total assets	(391,284)		(747,877)
Current liabilities:
Accounts payable to vendors	(1,733)		(1,757)
Undistributed oil and gas proceeds	0		0
Accrued interest	0		0
Asset retirement obligations	0		0
Current portion of long-term debt	0
Other current liabilities	0		0
Total current liabilities	(1,733)		(1,757)
Long-term debt	0		0
Asset retirement obligations	0		0
Other long-term liabilities	0		0
Total liabilities not subject to compromise	(1,733)
Liabilities subject to compromise	0
Total liabilities	(1,733)		(1,757)
Commitments and contingencies
Stockholders’ equity:
Common stock	0		0
Treasury stock	0		0
Additional paid-in capital	(1,408,745)		(1,454,372)
Accumulated deficit	1,019,194		720,130
Accumulated other comprehensive income			(11,878)
Total stockholders’ equity	(389,551)		(746,120)
Total liabilities and stockholders’ equity	(391,284)		(747,877)
Parent
Current assets:
Cash and cash equivalents	150,537		9,681	72,886	246,294
Accounts receivable	18,745		10,597
Fair value of derivative contracts			0
Current income tax receivable	26,086		46,174
Other current assets	10,151		6,848
Total current assets	205,519		73,300
Oil and gas properties, full cost method:
Proved	1,964,046		1,875,152
Less: accumulated DD&A	(1,964,046)		(1,874,622)
Net proved oil and gas properties	0		530
Unevaluated	251,955		253,308
Other property and equipment, net	26,213		29,289
Other assets, net	25,570		16,612
Investment in subsidiary	389,475		745,033
Total assets	898,732		1,118,072
Current liabilities:
Accounts payable to vendors	13,742		16,063
Undistributed oil and gas proceeds	14,170		5,216
Accrued interest	809		9,022
Asset retirement obligations	0		0
Current portion of long-term debt	408
Other current liabilities	18,602		40,161
Total current liabilities	47,731		70,462
Long-term debt	352,376		1,060,955
Asset retirement obligations	8,410		1,240
Other long-term liabilities	17,315		25,204
Total liabilities not subject to compromise	425,832
Liabilities subject to compromise	1,110,182
Total liabilities	1,536,014		1,157,861
Commitments and contingencies
Stockholders’ equity:
Common stock	56		55
Treasury stock	(860)		(860)
Additional paid-in capital	1,659,731		1,648,687
Accumulated deficit	(2,296,209)		(1,705,623)
Accumulated other comprehensive income			17,952
Total stockholders’ equity	(637,282)		(39,789)
Total liabilities and stockholders’ equity	898,732		1,118,072
Guarantor Subsidiary
Current assets:
Cash and cash equivalents	40,044		2	1,450	84,290
Accounts receivable	31,452		39,190
Fair value of derivative contracts			38,576
Current income tax receivable	0		0
Other current assets	0		0
Total current assets	71,496		77,768
Oil and gas properties, full cost method:
Proved	7,608,036		7,458,262
Less: accumulated DD&A	(7,170,242)		(6,686,849)
Net proved oil and gas properties	437,794		771,413
Unevaluated	121,765		186,735
Other property and equipment, net	0		0
Other assets, net	904		826
Investment in subsidiary	76		0
Total assets	632,035		1,036,742
Current liabilities:
Accounts payable to vendors	7,972		67,901
Undistributed oil and gas proceeds	903		776
Accrued interest	0		0
Asset retirement obligations	88,000		20,400
Current portion of long-term debt	0
Other current liabilities	0		551
Total current liabilities	96,875		89,628
Long-term debt	0		0
Asset retirement obligations	145,609		203,335
Other long-term liabilities	0		0
Total liabilities not subject to compromise	242,484
Liabilities subject to compromise	0
Total liabilities	242,484		292,963
Commitments and contingencies
Stockholders’ equity:
Common stock	0		0
Treasury stock	0		0
Additional paid-in capital	1,300,547		1,344,577
Accumulated deficit	(910,996)		(624,824)
Accumulated other comprehensive income			24,026
Total stockholders’ equity	389,551		743,779
Total liabilities and stockholders’ equity	632,035		1,036,742
Non- Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	0		1,076	$ 152	$ 640
Accounts receivable	0		0
Fair value of derivative contracts			0
Current income tax receivable	0		0
Other current assets	0		33
Total current assets	0		1,109
Oil and gas properties, full cost method:
Proved	44,154		42,484
Less: accumulated DD&A	(44,154)		(42,484)
Net proved oil and gas properties	0		0
Unevaluated	0		0
Other property and equipment, net	0		0
Other assets, net	0		1,035
Investment in subsidiary	0		1,088
Total assets	0		3,232
Current liabilities:
Accounts payable to vendors	0		0
Undistributed oil and gas proceeds	0		0
Accrued interest	0		0
Asset retirement obligations	0		891
Current portion of long-term debt	0
Other current liabilities	0		0
Total current liabilities	0		891
Long-term debt	0		0
Asset retirement obligations	0		0
Other long-term liabilities	0		0
Total liabilities not subject to compromise	0
Liabilities subject to compromise	0
Total liabilities	0		891
Commitments and contingencies
Stockholders’ equity:
Common stock	0		0
Treasury stock	0		0
Additional paid-in capital	108,198		109,795
Accumulated deficit	(108,198)		(95,306)
Accumulated other comprehensive income			(12,148)
Total stockholders’ equity	0		2,341
Total liabilities and stockholders’ equity	$ 0		$ 3,232