Consolidated Statements Of Operations (USD $)
In Thousands, except Per Share data, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Revenues:        
Oil and gas $ 53,161 $ 42,565 $ 100,819 $ 93,270
Derivative gains, net 6,358 46,309 4,150 31,768
Revenues 59,519 88,874 104,969 125,038
Costs and expenses:        
Oil and gas production 13,927 11,047 28,014 22,019
Production and ad valorem taxes 4,333 4,033 8,480 7,827
Depletion, depreciation and amortization 7,941 4,986 14,825 9,818
General and administrative 1,843 1,773 3,741 3,660
Accretion of discount on asset retirement obligations 207 190 414 378
Interest 984 509 1,821 818
Other 0 315 0 748
Total cost and expenses 29,235 22,853 57,295 45,268
Income before income taxes 30,284 66,021 47,674 79,770
Income tax provision (366) (772) (586) (951)
Net income 29,918 65,249 47,088 78,819
Allocation of net income applicable to the Partnership:        
General partner's interest 30 65 47 79
Limited partners' interest 29,805 64,997 46,934 78,538
Unvested participating securities' interest 83 187 107 202
Net income applicable to the Partnership $ 29,918 $ 65,249 $ 47,088 $ 78,819
Net income per common unit - basic and diluted $ 0.83 $ 1.82 $ 1.31 $ 2.20
Weighted average common units outstanding - basic and diluted 35,714 35,714 35,714 35,714
Distributions declared per common unit $ 0.52 $ 0.52 $ 1.04 $ 1.03