Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Cash flows from operating activities:
Net income	$ (65,296)	[1]	$ 55,440	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	60,592		57,478
Accretion of asset retirement obligations	4,313		3,490
Recognition of unit-based awards	3,399		3,185
Loss (gain) on derivative contracts, net	91,215		(34,205)
Cash received (paid) on settlement of derivative contracts	(2,933)		14,398
Loss on deferred Class B unit obligation	11,972
Other items	4,249		2,999
Changes in operating assets and liabilities:
Accounts receivable and other assets	(24,693)		(14,108)
Accounts payable and other liabilities	(3,669)		4,542
Net cash provided by operating activities	79,149		93,219
Cash flows from investing activities:
Additions to oil and natural gas properties	(73,153)		(39,028)
Acquisitions	(40,434)		(2,210)
Proceeds from sale of available-for-sale securities	893
Purchases of available-for-sale securities	(436)
Net cash used in investing activities	(113,130)		(41,238)
Cash flows from financing activities:
Proceeds from issuance of units			80
Management incentive fee to the general partner	(1,399)		(748)
Distributions to unitholders	(70,964)		(70,752)
Units withheld for employee payroll tax obligation	(601)		(17)
Proceeds from bank borrowings	123,000		15,000
Repayments on bank borrowings	(23,000)		(5,000)
Deferred financing costs			(1,826)
Other			(888)
Net cash provided by (used in) financing activities	27,036		(64,151)
Increase (decrease) in cash	(6,945)		(12,170)
Cash and cash equivalents at beginning of period	13,360		31,836
Cash and cash equivalents at ending of period	$ 6,415		$ 19,666

[1] Includes net income attributable to noncontrolling interest