Supplemental Oil and Gas Disclosures (Unaudited) (Details) bbl in Thousands, Mcf in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Boe location $ / bbl bbl Mcf	Dec. 31, 2015 USD ($) Boe $ / bbl bbl Mcf	Dec. 31, 2014 USD ($) Boe $ / bbl bbl Mcf
Capitalized costs relating to oil and gas producing activities [Abstract]
Proved oil and gas properties	$ 794,634	$ 787,683
Unproved properties	0	0
Total	794,634	787,683
Accumulated depreciation, depletion, amortization and impairment	(680,861)	(590,432)
Net capitalized costs	113,773	197,251
Cost incurred in oil and gas property acquisition and development activities [Abstract]
Development costs	18,262	68,631	$ 189,322
Exploration costs	12,529	0	0
Property acquisition costs	0	0	0
Unproved	0	0	0
Total	30,791	68,631	189,322
Results of operations for oil and gas producing activities [Abstract]
Revenues	56,493	67,002	133,701
Production costs	(23,659)	(29,753)	(37,337)
Depreciation, depletion, and amortization	(22,803)	(38,040)	(42,945)
Proved property impairment	(67,626)	(128,573)	0
Results of operations from oil and gas producing activities (excluding corporate overhead and interest costs)	$ (57,595)	$ (129,364)	$ 53,419
Depletion per barrel of oil equivalent | $ / bbl	10.08	17.44	20.39
Oil [Member]
Proved developed and undeveloped reserves [Abstract]
Balance | bbl	24,131	29,390	20,915
Revisions of previous estimates | bbl	1,379	(9,485)	2,697
Extensions and discoveries | bbl	1,183	5,679	7,780
Sales of minerals in place | bbl	(1,112)	(13)	(608)
Production | bbl	(1,372)	(1,440)	(1,394)
Balance | bbl	24,209	24,131	29,390
Proved Developed Reserves [Abstract]
Proved Developed Reserves | bbl	7,818	10,022	10,162
Proved Undeveloped Reserves [Abstract]
Proved Undeveloped Reserves | bbl	16,391	14,109	19,228
NGL [Member]
Proved developed and undeveloped reserves [Abstract]
Balance | bbl	6,556	3,708	2,038
Revisions of previous estimates | bbl	2,300	(505)	1,021
Extensions and discoveries | bbl	157	3,591	868
Sales of minerals in place | bbl	(6)	0	(12)
Production | bbl	(363)	(238)	(207)
Balance | bbl	8,644	6,556	3,708
Proved Developed Reserves [Abstract]
Proved Developed Reserves | Mcf	3	2	2
Proved Undeveloped Reserves [Abstract]
Proved Undeveloped Reserves | Mcf	6	5	2
Natural Gas [Member]
Proved developed and undeveloped reserves [Abstract]
Balance | Mcf	75,027	55,853	48,109
Revisions of previous estimates | Mcf	(1,537)	(8,002)	7,383
Extensions and discoveries | Mcf	1,179	30,372	6,893
Sales of minerals in place | Mcf	(680)	(181)	(3,614)
Production | Mcf	(3,160)	(3,015)	(2,918)
Balance | Mcf	70,829	75,027	55,853
Proved Developed Reserves [Abstract]
Proved Developed Reserves | Mcf	27,792	31,298	34,677
Proved Undeveloped Reserves [Abstract]
Proved Undeveloped Reserves | Mcf	43,037	43,729	21,176
Oil Equivalents [Member]
Proved developed and undeveloped reserves [Abstract]
Balance | Boe	43,190,000	42,406,000	30,970,000
Revisions of previous estimates | Boe	5,005,000
Extensions and discoveries | Boe	1,537,000	14,332,000	9,797,000
Sales of minerals in place | Boe	(1,232,000)	(43,000)	(1,223,000)
Production | Boe	(2,262,000)	(2,181,000)	(2,088,000)
Balance | Boe	44,657,000	43,190,000	42,406,000
Proved Developed Reserves [Abstract]
Proved Developed Reserves | Boe	15,018,000	17,194,000	17,948,000
Proved Undeveloped Reserves [Abstract]
Proved Undeveloped Reserves | Boe	29,639,000	25,996,000	24,459,000
NORTH DAKOTA | Oil Equivalents [Member]
Proved Undeveloped Reserves [Abstract]
Proved Developed and Undeveloped Reserve, Net (Energy), Period Increase (Decrease) | Boe	0
Gas and Oil Area, Undeveloped, Additional Down-Spaced Locations | location	8
Proved Undeveloped Reserves (Energy) | Boe	6,500,000,000
North Dakota - Bakken [Member] | Oil Equivalents [Member]
Proved Undeveloped Reserves [Abstract]
Gas and Oil Area, Undeveloped, Additional Locations | location	28
Proved Undeveloped Reserves (Energy) | Boe	21
North Dakota - Three Forks [Member] | Oil Equivalents [Member]
Proved Undeveloped Reserves [Abstract]
Gas and Oil Area, Undeveloped, Additional Locations | location	20
Proved Undeveloped Reserves (Energy) | Boe	4,900,000,000
Texas - Montoya [Member] | Oil Equivalents [Member]
Proved Undeveloped Reserves [Abstract]
Gas and Oil Area, Undeveloped, Additional Locations | location	6
Proved Undeveloped Reserves (Energy) | Boe	6.5