Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ (14,396)	$ (8,174)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	29,836	30,815
Accretion of asset retirement obligations	2,134	1,732
Recognition of unit-based awards	1,743	1,026
Loss on derivative contracts, net	23,648	16,124
Cash received (paid) on settlement of derivative contracts	(273)	8,165
Loss on Deferred Class B unit obligation	5,240
Other items	1,643	1,400
Changes in operating assets and liabilities:
Accounts receivable and other assets	(342)	(14,997)
Accounts payable and other liabilities	(7,063)	(2,169)
Net cash provided by operating activities	42,170	33,922
Cash flows from investing activities:
Additions to oil and natural gas properties	(29,833)	(18,507)
Acquisitions	(29,016)	2,277
Proceeds from sale of available-for-sale securities	614
Purchases of available-for-sale securities	(189)
Net cash used in investing activities	(58,424)	(16,230)
Cash flows from financing activities:
Proceeds from issuance of units		80
Management incentive fee to the general partner	(1,399)
Distributions to unitholders	(35,422)	(32,284)
Units withheld for employee payroll tax obligation	(25)	(17)
Proceeds from bank borrowings	63,000
Deferred financing costs		(1,848)
Net cash provided by (used in) financing activities	26,154	(33,948)
Increase (decrease) in cash	9,900	(16,256)
Cash and cash equivalents at beginning of period	13,360	31,836
Cash and cash equivalents at ending of period	$ 23,260	$ 15,580