Guarantor Financial Statements - Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net loss	$ (195,761)	$ (152,906)	$ (384,545)	$ (480,294)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	46,231	77,951	107,789	164,373
Write-down of oil and gas properties	118,649	224,294	247,853	715,706
Accretion expense	10,082	6,408	20,065	12,817
Deferred income tax provision (benefit)	6,182	(85,048)	9,059	(264,954)
Settlement of asset retirement obligations			(10,706)	(35,923)
Non-cash stock compensation expense			4,682	6,028
Non-cash derivative expense			1,025	7,931
Non-cash interest expense			9,403	8,737
Other non-cash expense			6,081	0
Change in current income taxes			(3,187)	7,206
Non-cash loss from investment in subsidiaries				0
Change in intercompany receivables/payables				0
(Increase) decrease in accounts receivable			9,755	23,047
Increase in other current assets			(5,283)	(1,959)
(Increase) decrease in inventory				0
Decrease in accounts payable			(321)	(7,826)
Decrease in other current liabilities			(5,920)	(8,720)
Other			(7,880)	(504)
Net cash (used in) provided by operating activities			(2,130)	145,665
Cash flows from investing activities:
Investment in oil and gas properties			(179,311)	(264,355)
Proceeds from sale of oil and gas properties, net of expenses			0	10,100
Investment in fixed and other assets			(898)	(727)
Change in restricted funds			1,045	179,475
Investment in subsidiaries				0
Net cash used in investing activities			(179,164)	(75,507)
Cash flows from financing activities:
Proceeds from bank borrowings			477,000	5,000
Repayments of bank borrowings			(135,500)	(5,000)
Repayments of building loan			(189)	0
Deferred financing costs			(900)	0
Equity proceeds from parent				0
Net payments for share-based compensation			(673)	(3,069)
Net cash provided by (used in) financing activities			339,738	(3,069)
Effect of exchange rate changes on cash			(9)	78
Net change in cash and cash equivalents			158,435	67,167
Cash and cash equivalents, beginning of period			10,759	74,488
Cash and cash equivalents, end of period	169,194	141,655	169,194	141,655
Parent
Cash flows from operating activities:
Net loss	(195,761)	(152,906)	(384,545)	(480,294)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	10,470	44,052	19,064	86,164
Write-down of oil and gas properties	6,534	179,125	15,858	670,537
Accretion expense	58	91	116	182
Deferred income tax provision (benefit)	0	(77,863)	0	(274,097)
Settlement of asset retirement obligations			0	(14)
Non-cash stock compensation expense			4,682	6,028
Non-cash derivative expense				0
Non-cash interest expense			9,403	8,737
Change in current income taxes			(3,187)	7,206
Non-cash loss from investment in subsidiaries			230,729	(45,174)
Change in intercompany receivables/payables			(1,658)	15,070
(Increase) decrease in accounts receivable			(8,471)	16,968
Increase in other current assets			(5,316)	(1,895)
(Increase) decrease in inventory				(2,415)
Decrease in accounts payable			2,226	(500)
Decrease in other current liabilities			(5,565)	(8,409)
Other			(7,372)	(71)
Net cash (used in) provided by operating activities			(134,036)	(1,977)
Cash flows from investing activities:
Investment in oil and gas properties			(45,292)	(128,333)
Proceeds from sale of oil and gas properties, net of expenses				0
Investment in fixed and other assets			(898)	(727)
Change in restricted funds			0	177,647
Investment in subsidiaries				0
Net cash used in investing activities			(46,190)	48,587
Cash flows from financing activities:
Proceeds from bank borrowings			477,000	5,000
Repayments of bank borrowings			(135,500)	(5,000)
Repayments of building loan			(189)
Deferred financing costs			(900)
Equity proceeds from parent				0
Net payments for share-based compensation			(673)	(3,069)
Net cash provided by (used in) financing activities			339,738	(3,069)
Effect of exchange rate changes on cash				0
Net change in cash and cash equivalents			159,512	43,541
Cash and cash equivalents, beginning of period			9,681	72,886
Cash and cash equivalents, end of period	169,193	116,427	169,193	116,427
Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(99,445)	45,065	(224,284)	74,092
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	35,761	33,899	88,725	78,209
Write-down of oil and gas properties	112,114	0	231,645	0
Accretion expense	10,024	6,317	19,949	12,635
Deferred income tax provision (benefit)	6,182	9,082	9,059	25,410
Settlement of asset retirement obligations			(9,807)	(35,909)
Non-cash stock compensation expense				0
Non-cash derivative expense			1,025	7,931
Non-cash interest expense				0
Change in current income taxes				0
Non-cash loss from investment in subsidiaries				0
Change in intercompany receivables/payables			1,658	(24,802)
(Increase) decrease in accounts receivable			19,109	6,079
Increase in other current assets				0
(Increase) decrease in inventory				2,415
Decrease in accounts payable			(2,547)	(7,326)
Decrease in other current liabilities			(355)	(311)
Other			(508)	(433)
Net cash (used in) provided by operating activities			133,669	137,990
Cash flows from investing activities:
Investment in oil and gas properties			(133,670)	(124,506)
Proceeds from sale of oil and gas properties, net of expenses				10,100
Investment in fixed and other assets				0
Change in restricted funds				0
Investment in subsidiaries				0
Net cash used in investing activities			(133,670)	(114,406)
Cash flows from financing activities:
Proceeds from bank borrowings				0
Repayments of bank borrowings				0
Equity proceeds from parent				0
Net payments for share-based compensation				0
Net cash provided by (used in) financing activities				0
Effect of exchange rate changes on cash				0
Net change in cash and cash equivalents			(1)	23,584
Cash and cash equivalents, beginning of period			2	1,450
Cash and cash equivalents, end of period	1	25,034	1	25,034
Non- Guarantor Subsidiaries
Cash flows from operating activities:
Net loss	(3)	(57,836)	(12,889)	(57,836)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization			0	0
Write-down of oil and gas properties	1	45,169	350	45,169
Accretion expense				0
Deferred income tax provision (benefit)	0	(16,267)	0	(16,267)
Settlement of asset retirement obligations			(899)	0
Non-cash stock compensation expense				0
Non-cash derivative expense				0
Non-cash interest expense				0
Other non-cash expense			6,081
Change in current income taxes				0
Non-cash loss from investment in subsidiaries			6,444	28,918
Change in intercompany receivables/payables			0	9,732
(Increase) decrease in accounts receivable			(883)	0
Increase in other current assets			33	(64)
(Increase) decrease in inventory				0
Decrease in accounts payable				0
Decrease in other current liabilities				0
Other				0
Net cash (used in) provided by operating activities			(1,763)	9,652
Cash flows from investing activities:
Investment in oil and gas properties			(349)	(11,516)
Proceeds from sale of oil and gas properties, net of expenses				0
Investment in fixed and other assets				0
Change in restricted funds			1,045	1,828
Investment in subsidiaries			717	(9,684)
Net cash used in investing activities			1,413	(19,372)
Cash flows from financing activities:
Proceeds from bank borrowings				0
Repayments of bank borrowings				0
Equity proceeds from parent			(717)	9,684
Net payments for share-based compensation				0
Net cash provided by (used in) financing activities			(717)	9,684
Effect of exchange rate changes on cash			(9)	78
Net change in cash and cash equivalents			(1,076)	42
Cash and cash equivalents, beginning of period			1,076	152
Cash and cash equivalents, end of period	0	194	0	194
Eliminations
Cash flows from operating activities:
Net loss	99,448	12,771	237,173	(16,256)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization			0	0
Write-down of oil and gas properties				0
Accretion expense				0
Deferred income tax provision (benefit)	0		0	0
Settlement of asset retirement obligations				0
Non-cash stock compensation expense				0
Non-cash derivative expense				0
Non-cash interest expense				0
Change in current income taxes				0
Non-cash loss from investment in subsidiaries			(237,173)	16,256
Change in intercompany receivables/payables				0
(Increase) decrease in accounts receivable				0
Increase in other current assets				0
(Increase) decrease in inventory				0
Decrease in accounts payable				0
Decrease in other current liabilities				0
Other				0
Net cash (used in) provided by operating activities			0	0
Cash flows from investing activities:
Investment in oil and gas properties				0
Proceeds from sale of oil and gas properties, net of expenses				0
Investment in fixed and other assets				0
Change in restricted funds				0
Investment in subsidiaries			(717)	9,684
Net cash used in investing activities			(717)	9,684
Cash flows from financing activities:
Proceeds from bank borrowings				0
Repayments of bank borrowings				0
Equity proceeds from parent			717	(9,684)
Net payments for share-based compensation				0
Net cash provided by (used in) financing activities			717	(9,684)
Effect of exchange rate changes on cash				0
Net change in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	$ 0	$ 0	$ 0	$ 0