Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues:
Oil, natural gas and natural gas liquids revenues	$ 72,669	$ 76,801
Transportation and marketing-related revenues	1,033	930
Total revenues	73,702	77,731
Operating costs and expenses:
Lease operating expenses	26,094	28,600
Cost of purchased natural gas	743	645
Dry hole and exploration costs	417	2,173
Production taxes	2,916	3,282
Asset retirement obligations accretion expense	1,354	1,208
Depreciation, depletion and amortization	30,833	24,591
General and administrative expenses	12,622	12,117
Impairment of oil and natural gas properties	5,169	635
Total operating costs and expenses	80,148	73,251
Operating income	(6,446)	4,480
Other income (expense), net:
Realized gains on derivatives, net	10,759	24,190
Unrealized gains on derivatives, net	(38,273)	11,661
Interest expense	(12,829)	(11,084)
Other (expense) income, net	187	4
Total other income, net	(40,156)	24,771
Income before income taxes and equity in losses of unconsolidated affiliates	(46,602)	29,251
Income taxes	(177)	(658)
Income before equity in losses of unconsolidated affiliates	(46,779)	28,593
Equity in losses of unconsolidated affiliates	198
Net (loss) income	(46,581)	28,593
Limited partners' interest in net income	$ (46,147)	$ 28,021
Net income per limited partner unit:
Basic	(1.08)	0.69
Diluted	(1.08)	0.69
Weighted average limited partner units outstanding:
Basic	42,556	40,440
Diluted	42,556	40,760
Distributions declared per unit	$ 0.768	$ 0.764