Supplemental Oil and Gas Reserve Information (Details) Mcf in Thousands, MBoe in Thousands, MBbls in Thousands	12 Months Ended
	Dec. 31, 2016 MBoe MBbls Mcf	Dec. 31, 2015 MBoe MBbls Mcf	Dec. 31, 2014 MBoe MBbls Mcf
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (MBOE) (at beginning) | MBoe	46,569	75,430	70,015
Extensions and discoveries (MBOE) | MBoe	4,077	3,542	23,336
Revisions (MBOE) | MBoe	(168)	(26,158)	(10,101)
Sales of minerals-in-place (MBOE) | MBoe	(10,728)	(472)	(2,057)
Production (MBOE) | MBoe	(4,996)	(5,773)	(5,763)
Proved developed and undeveloped reserves, net (MBOE) (at ending) | MBoe	34,754	46,569	75,430
Proved developed reserves (MBOE) | MBoe	21,978	36,280	42,239
Proved developed and undeveloped reserves, upward revisions of previous estimates attributable to well performance | MBoe	11,670
Proved developed and undeveloped reserves, downward revisions | MBoe	11,838
Oil
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning)	33,076	53,867	48,665
Extensions and discoveries	2,864	2,669	19,032
Revisions	553	(18,912)	(7,786)
Sales of minerals-in-place	(8,523)	(291)	(1,850)
Production	(3,623)	(4,257)	(4,194)
Proved developed and undeveloped reserves, net (at end)	24,347	33,076	53,867
Proved developed reserves (volume)	14,540	25,349	29,059
Natural Gas Liquids
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning)	5,468	8,967	8,487
Extensions and discoveries	604	407	2,298
Revisions	(48)	(3,344)	(1,160)
Sales of minerals-in-place	(656)	(12)	(73)
Production	(557)	(550)	(585)
Proved developed and undeveloped reserves, net (at end)	4,811	5,468	8,967
Proved developed reserves (volume)	3,335	4,266	4,668
Natural Gas
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, net (at beginning) | Mcf	48,147	75,575	77,179
Extensions and discoveries | Mcf	3,651	2,796	12,034
Revisions | Mcf	(4,036)	(23,414)	(6,934)
Sales of minerals-in-place | Mcf	(9,292)	(1,016)	(803)
Production | Mcf	(4,893)	(5,794)	(5,901)
Proved developed and undeveloped reserves, net (at end) | Mcf	33,577	48,147	75,575
Proved developed reserves (volume) | Mcf	24,620	39,987	51,072