Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash	$ 605	$ 1,601
Accounts receivable - trade	19,332	15,651
Inventories	1,186	1,388
Prepaid expenses	175	228
Deferred tax assets, current	146	89
Derivative assets, current	4,333	4,553
Total current assets	25,777	23,510
Oil and gas properties, using the successful efforts method of accounting:
Proved properties	592,834	556,915
Unproved properties	5,480	5,682
Accumulated depletion, depreciation and amortization	(170,426)	(163,542)
Total property, plant and equipment	427,888	399,055
Derivative assets, noncurrent	7,465	7,227
Other, net	1,033	1,097
Total assets	462,163	430,889
Accounts payable:
Trade	21,071	15,557
Due to affiliates	519	1,277
Interest payable	168	9
Income taxes payable to affiliate	127	70
Derivative liabilities, current	12,711	13,390
Asset retirement obligations	600	900
Other current liabilities	193	146
Total current liabilities	35,389	31,349
Long-term debt	154,000	126,000
Derivative liabilities, noncurrent	263	150
Deferred tax liabilities, noncurrent	376	156
Asset retirement obligations	11,401	11,201
Other noncurrent liabilities	289	400
Partners' equity:
General partner's interest - 35,750 general partner units issued and outstanding	414	416
Limited partners' interest - 35,713,700 common units issued and outstanding	260,031	261,217
Total partners' equity	260,445	261,633
Commitments and contingencies
Total liabilities and partners' equity	$ 462,163	$ 430,889