Supplementary Financial Information on Oil and Natural Gas Exploration, Development and Production Activities (Unaudited) - Proved Oil and Natural Gas Reserves (Details)	12 Months Ended
	Dec. 31, 2015 Mcf bbl	Dec. 31, 2014 Mcf bbl
Proved developed and undeveloped reserves:
Ownership percentage by noncontrolling owners	50.00%
Natural Gas
Proved developed and undeveloped reserves:
Proved developed and undeveloped reserves, at the beginning of year | Mcf	600,000	723,190
Purchase (sale) of natural gas properties in place | Mcf	0	(46,770)
Discoveries and extensions | Mcf	26,680	0
Revisions | Mcf	(410,362)	(30,843)
Production | Mcf	(37,568)	(45,577)
Proved reserves, at the end of year | Mcf	178,750	600,000
Natural Gas | Consolidated Entities
Proved developed and undeveloped reserves:
Proved developed and undeveloped reserves, at the beginning of year | bbl	10,350
Proved reserves, at the end of year | bbl	20,690	10,350
Oil
Proved developed and undeveloped reserves:
Proved developed and undeveloped reserves, at the beginning of year | bbl	20,700	49,020
Purchase (sale) of natural gas properties in place | bbl	0	(26,290)
Discoveries and extensions | bbl	30,720	1,175
Revisions | bbl	2,112	3,700
Production | bbl	(12,152)	(6,905)
Proved reserves, at the end of year | bbl	41,380	20,700
Oil | Consolidated Entities
Proved developed and undeveloped reserves:
Proved developed and undeveloped reserves, at the beginning of year | Mcf	300,000
Proved reserves, at the end of year | Mcf	89,375	300,000