Supplemental Oil and Gas Reserve Information (Details)	12 Months Ended
	Dec. 31, 2014 MBoe	Dec. 31, 2013 MBoe	Dec. 31, 2012 MBoe
Reserve Quantities [Line Items]
Proved Developed and Undeveloped Reserves, Net (BOE) (at beginning)	70,015,000	75,357,000	64,349,000
Proved Developed and Undeveloped Reserves, Extensions, Discoveries, and Additions (BOE)	23,336,000	27,666,000	20,443,000
Proved Developed and Undeveloped Reserves, Downward Revisions of Previous Estimates (MBOE)	10,101,000	(901,000)	(6,615,000)
Proved Developed and Undeveloped Reserves, Purchases of Minerals in Place (MBOE)			3,504,000
Proved Developed and Undeveloped Reserves, Sales of Minerals in Place (BOE)	(2,057,000)	(26,852,000)	(725,000)
Proved Developed and Undeveloped Reserves, Production (BOE)	(5,763,000)	(5,255,000)	(5,599,000)
Proved Developed and Undeveloped Reserves, Net (BOE) (at end)	75,430,000	70,015,000	75,357,000
Proved Developed Reserves (BOE)	42,239,000	38,255,000	43,354,000
Proved Developed And Undeveloped Reserves, Downward Revisions Of Previous Estimates Related To Reclassifications Caused By SEC Development Guidelines	4,911,000
Proved developed and undeveloped reserves, downward revisions of previous estimates attributable to well performance	4,837,000
Proved Developed and Undeveloped Reserves, Downward Revisions of Previous Estimates Attributable to Effects of Lower Commodity Prices	353,000
Oil
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning)	48,665,000	49,119,000	44,919,000
Extensions and discoveries	19,032,000	20,540,000	13,501,000
Proved Developed and Undeveloped Reserves, Revisions of Previous Estimates	(7,786,000)	85,000	(7,303,000)
Purchases of minerals-in-place			2,456,000
Sales of minerals-in-place	(1,850,000)	(17,387,000)	(633,000)
Production	(4,194,000)	(3,692,000)	(3,821,000)
Proved developed and undeveloped reserves, net (at end)	53,867,000	48,665,000	49,119,000
Proved Developed Reserves (Volume)	29,059,000	25,989,000	27,641,000
Natural Gas Liquids
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning)	8,487,000	9,182,000	4,617,000
Extensions and discoveries	2,298,000	3,562,000	3,175,000
Proved Developed and Undeveloped Reserves, Revisions of Previous Estimates	(1,160,000)	1,806,000	1,805,000
Purchases of minerals-in-place			18,000
Sales of minerals-in-place	(73,000)	(5,531,000)	0
Production	(585,000)	(532,000)	(433,000)
Proved developed and undeveloped reserves, net (at end)	8,967,000	8,487,000	9,182,000
Proved Developed Reserves (Volume)	4,668,000	4,293,000	5,044,000
Natural Gas
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning)	77,179,000	102,336,000	88,876,000
Extensions and discoveries	12,034,000	21,389,000	22,604,000
Proved Developed and Undeveloped Reserves, Revisions of Previous Estimates	(6,934,000)	(16,753,000)	(6,699,000)
Purchases of minerals-in-place			6,182,000
Sales of minerals-in-place	(803,000)	(23,605,000)	(555,000)
Production	(5,901,000)	(6,188,000)	(8,072,000)
Proved developed and undeveloped reserves, net (at end)	75,575,000	77,179,000	102,336,000
Proved Developed Reserves (Volume)	51,072,000	47,839,000	64,013,000