Subsidiary Guarantors (Condensed Consolidated Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$ 134,464	$ 141,818
Cash flows from investing activities:
Additions to oil and natural gas properties	(119,437)	(65,898)
Acquisitions	(44,251)	(101,696)
Divestitures of oil and gas properties	1,300
Proceeds from sale of available-for-sale securities	3,749	4,643
Purchases of available-for-sale securities	(4,022)	(4,268)
Net cash (used in) provided by investing activities	(162,661)	(167,219)
Cash flows from financing activities:
Distributions to unitholders	(106,582)	(106,226)
Proceeds from bank borrowings	178,000	150,000
Repayments on bank/intercompany borrowings	(38,000)	(20,000)
Other	(2,422)	(4,145)
Net cash (used in) provided by financing activities	30,996	19,629
Increase (decrease) in cash	2,799	(5,772)
Cash and cash equivalents at beginning of period	13,360	31,836
Cash and cash equivalents at ending of period	16,159	26,064
Parent Co - Issuer [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(28,242)	(28,050)
Cash flows from investing activities:
Distributions from subsidiaries	137,278	136,449
Net cash (used in) provided by investing activities	137,278	136,449
Cash flows from financing activities:
Distributions to unitholders	(106,582)	(106,226)
Other	(2,422)	(2,241)
Net cash (used in) provided by financing activities	(109,004)	(108,467)
Increase (decrease) in cash	32	(68)
Cash and cash equivalents at beginning of period	78	68
Cash and cash equivalents at ending of period	110
Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	160,912	169,511
Cash flows from investing activities:
Additions to oil and natural gas properties	(117,650)	(65,898)
Acquisitions	(44,251)	(105,177)
Divestitures of oil and gas properties	1,300
Net cash (used in) provided by investing activities	(160,601)	(171,075)
Cash flows from financing activities:
Proceeds from bank borrowings	178,000	150,000
Repayments on bank/intercompany borrowings	(38,000)	(20,000)
Repayments on intercompany borrowings		(33,213)
Distributions to Parent	(137,278)	(103,236)
Other		(1,904)
Net cash (used in) provided by financing activities	2,722	(8,353)
Increase (decrease) in cash	3,033	(9,917)
Cash and cash equivalents at beginning of period	10,575	31,768
Cash and cash equivalents at ending of period	13,608	21,851
Non-Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	1,794	357
Cash flows from investing activities:
Additions to oil and natural gas properties	(1,787)
Acquisitions		3,481
Proceeds from sale of available-for-sale securities	3,749	4,643
Purchases of available-for-sale securities	(4,022)	(4,268)
Net cash (used in) provided by investing activities	(2,060)	3,856
Cash flows from financing activities:
Increase (decrease) in cash	(266)	4,213
Cash and cash equivalents at beginning of period	2,707
Cash and cash equivalents at ending of period	2,441	4,213
Eliminations [Member]
Cash flows from investing activities:
Distributions from subsidiaries	(137,278)	(136,449)
Net cash (used in) provided by investing activities	(137,278)	(136,449)
Cash flows from financing activities:
Repayments on intercompany borrowings		33,213
Distributions to Parent	137,278	103,236
Net cash (used in) provided by financing activities	$ 137,278	$ 136,449