Derivative Activities - Schedule of Additional Information Related to Master Netting Arrangements with Derivative Counterparties (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Gross Amounts of Recognized Assets	$ 99,241	$ 77,079
Gross Amounts Offset in the Balance Sheet	(52,996)	(63,596)
Net Amounts of Assets Presented in the Balance Sheet	46,245	13,483
Gross Amounts of Recognized (Liabilities)	(110,224)	(253,096)
Gross Amounts Offset in the Balance Sheet	52,996	63,596
Net Amounts of (Liabilities) Presented in the Balance Sheet	(57,228)	(189,500)
Natural Gas | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	28,756	13,213
Gross Amounts Offset in the Balance Sheet	(19,019)	(11,425)
Net Amounts of Assets Presented in the Balance Sheet	9,737	1,788
Gross Amounts of Recognized (Liabilities)	(55,204)	(158,359)
Gross Amounts Offset in the Balance Sheet	19,019	11,425
Net Amounts of (Liabilities) Presented in the Balance Sheet	(36,185)	(146,934)
Natural Gas | Basis Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	905	12,535
Gross Amounts Offset in the Balance Sheet	(3,330)	(9,437)
Net Amounts of Assets Presented in the Balance Sheet	(2,425)	3,098
Gross Amounts of Recognized (Liabilities)	(21,287)	(687)
Gross Amounts Offset in the Balance Sheet	3,330	9,437
Net Amounts of (Liabilities) Presented in the Balance Sheet	(17,957)	8,750
Natural Gas | Collars
Derivative [Line Items]
Gross Amounts of Recognized Assets	9,650	6,298
Gross Amounts Offset in the Balance Sheet	(1,435)	(6,298)
Net Amounts of Assets Presented in the Balance Sheet	8,215	0
Gross Amounts of Recognized (Liabilities)	0	(2,625)
Gross Amounts Offset in the Balance Sheet	1,435	6,298
Net Amounts of (Liabilities) Presented in the Balance Sheet	1,435	3,673
Natural Gas | Puts
Derivative [Line Items]
Gross Amounts of Recognized Assets	19,563	18,159
Gross Amounts Offset in the Balance Sheet	(4,609)	(15,429)
Net Amounts of Assets Presented in the Balance Sheet	14,954	2,730
Gross Amounts of Recognized (Liabilities)	0	0
Gross Amounts Offset in the Balance Sheet	4,609	15,429
Net Amounts of (Liabilities) Presented in the Balance Sheet	4,609	15,429
Natural Gas | Calls
Derivative [Line Items]
Gross Amounts of Recognized Assets	0
Gross Amounts Offset in the Balance Sheet	(531)
Net Amounts of Assets Presented in the Balance Sheet	(531)
Gross Amounts of Recognized (Liabilities)	(531)	(1,041)
Gross Amounts Offset in the Balance Sheet	531	0
Net Amounts of (Liabilities) Presented in the Balance Sheet	0	(1,041)
Crude Oil | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	14,026	9,356
Gross Amounts Offset in the Balance Sheet	(1,532)	(3,489)
Net Amounts of Assets Presented in the Balance Sheet	12,494	5,867
Gross Amounts of Recognized (Liabilities)	(1,308)	(13,206)
Gross Amounts Offset in the Balance Sheet	1,532	3,489
Net Amounts of (Liabilities) Presented in the Balance Sheet	224	(9,717)
Commodity Contract NGLs (C2 - Ethane) | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	507	53
Gross Amounts Offset in the Balance Sheet	(251)	(53)
Net Amounts of Assets Presented in the Balance Sheet	256	0
Gross Amounts of Recognized (Liabilities)	(137)	(1,008)
Gross Amounts Offset in the Balance Sheet	251	53
Net Amounts of (Liabilities) Presented in the Balance Sheet	114	(955)
Commodity Contract NGLs (C3 - Propane) | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	4,531
Gross Amounts Offset in the Balance Sheet	(4,892)
Net Amounts of Assets Presented in the Balance Sheet	(361)
Gross Amounts of Recognized (Liabilities)	(12,164)	(32,437)
Gross Amounts Offset in the Balance Sheet	4,892	0
Net Amounts of (Liabilities) Presented in the Balance Sheet	(7,272)	(32,437)
Commodity Contract NGLs (C3 - Propane) | Spread Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	11,812	17,396
Gross Amounts Offset in the Balance Sheet	(11,812)	(17,396)
Net Amounts of Assets Presented in the Balance Sheet	0	0
Gross Amounts of Recognized (Liabilities)	(11,321)	(18,138)
Gross Amounts Offset in the Balance Sheet	11,812	17,396
Net Amounts of (Liabilities) Presented in the Balance Sheet	491	(742)
Commodity Contract NGLs (NC4 - Normal Butane) | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	6,970	4
Gross Amounts Offset in the Balance Sheet	(3,258)	(4)
Net Amounts of Assets Presented in the Balance Sheet	3,712	0
Gross Amounts of Recognized (Liabilities)	(3,395)	(13,419)
Gross Amounts Offset in the Balance Sheet	3,258	4
Net Amounts of (Liabilities) Presented in the Balance Sheet	(137)	(13,415)
Commodity Contract NGLs (C5 - Natural Gasoline) | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	2,405
Gross Amounts Offset in the Balance Sheet	(2,211)
Net Amounts of Assets Presented in the Balance Sheet	194
Gross Amounts of Recognized (Liabilities)	(4,877)	(12,176)
Gross Amounts Offset in the Balance Sheet	2,211	0
Net Amounts of (Liabilities) Presented in the Balance Sheet	(2,666)	(12,176)
Freight | Swaps
Derivative [Line Items]
Gross Amounts of Recognized Assets	116	65
Gross Amounts Offset in the Balance Sheet	(116)	(65)
Net Amounts of Assets Presented in the Balance Sheet	0	0
Gross Amounts of Recognized (Liabilities)	0	0
Gross Amounts Offset in the Balance Sheet	116	65
Net Amounts of (Liabilities) Presented in the Balance Sheet	$ 116	$ 65