Supplementary Information on Oil and Gas Operations—Unaudited - Proved Reserves (Details) Mcfe in Thousands, MMcf in Thousands, MBbls in Thousands	12 Months Ended
	Dec. 31, 2015 Mcfe MBbls MMcf	Dec. 31, 2014 Mcfe MBbls MMcf	Dec. 31, 2013 Mcfe MBbls MMcf
Oil
Proved Developed and Undeveloped Reserves [Abstract]
Proved reserves beginning balance | MBbls	2,437	3,031	1,635
Revisions of previous estimates | MBbls	(211)	(37)	(156)
Extensions, discoveries and other additions | MBbls	163	475	434
Purchase of producing properties | MBbls			1,833
Sale of reserves in place | MBbls	(54)	(229)	(34)
Production | MBbls	(529)	(803)	(681)
Proved reserves ending balance | MBbls	1,806	2,437	3,031
Proved developed reserves | MBbls	1,549	2,089	2,709
Proved undeveloped reserve | MBbls	257	348	322
Natural Gas Liquids
Proved Developed and Undeveloped Reserves [Abstract]
Proved reserves, ending balance	73,498	28,430	24,366
Revisions of previous estimates	(3,571)	2,894	804
Extensions, discoveries and other additions	16,078	49,990	6,099
Purchase of producing properties			1,915
Sale of reserves in place	(45,692)	(334)	0
Production	(5,487)	(7,482)	(4,754)
Proved reserves, ending balance	34,826	73,498	28,430
Proved undeveloped reserve	15,792	42,584	23,173
Proved developed reserves	19,034	30,914	5,257
Natural Gas
Proved Developed and Undeveloped Reserves [Abstract]
Proved reserves beginning balance | MMcf	309,025	250,109	188,264
Revisions of previous estimates | MMcf	(9,852)	9,976	38,383
Extensions, discoveries and other additions | MMcf	45,645	82,364	30,429
Purchase of producing properties | MMcf			22,274
Sale of reserves in place | MMcf	(186,972)	(2,396)	(15)
Production | MMcf	(25,502)	(31,028)	(29,226)
Proved reserves ending balance | MMcf	132,344	309,025	250,109
Proved developed reserves | MMcf	78,533	182,567	163,728
Proved undeveloped reserve | MMcf	53,811	126,458	86,381
Oil and Natural Gas Reserves
Proved Developed and Undeveloped Reserves [Abstract]
Proved reserves, ending balance	397,148	296,723	222,441
Revisions of previous estimates	(14,698)	12,650	38,247
Extensions, discoveries and other additions	62,702	135,205	39,132
Purchase of producing properties			35,187
Sale of reserves in place	(232,988)	(4,105)	(218)
Production	(34,160)	(43,325)	(38,066)
Proved reserves, ending balance	178,004	397,148	296,723
Proved undeveloped reserve	103,615	237,688	203,152
Proved developed reserves	74,389	159,460	93,571