Subsidiary Guarantors (Condensed Consolidated Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$ 202,145	$ 227,150	$ 112,557
Cash flows from investing activities:
Additions to oil and natural gas properties	(88,247)	(127,352)	(70,426)
Acquisitions, net of cash acquired	(128,234)	(468,009)	(3,044)
Proceeds from sale of available-for-sale securities	8,535
Purchases of available-for-sale securities	(10,249)
Net cash (used in) provided by investing activities	(218,195)	(592,279)	(72,143)
Cash flows from financing activities:
Distributions to unitholders	(141,582)	(96,472)	(46,026)
Proceeds from bank borrowings	180,000	476,500	275,000
Repayments on bank borrowings	(35,000)	(506,500)
Other	(5,844)
Net cash provided by (used in) financing activities	(2,426)	379,532	(25,176)
Increase (decrease) in cash	(18,476)	14,403	15,238
Cash and cash equivalents at beginning of period	31,836	17,433	2,195
Cash and cash equivalents at ending of period	13,360	31,836	17,433
Parent Co - Issuer [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(22,103)
Cash flows from investing activities:
Distributions from subsidiaries	167,470
Net cash (used in) provided by investing activities	167,470
Cash flows from financing activities:
Distributions to unitholders	(141,582)
Other	(3,775)
Net cash provided by (used in) financing activities	(145,357)
Increase (decrease) in cash	10
Cash and cash equivalents at beginning of period	68
Cash and cash equivalents at ending of period	78
Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	222,997
Cash flows from investing activities:
Additions to oil and natural gas properties	(87,936)
Acquisitions, net of cash acquired	(131,715)
Net cash (used in) provided by investing activities	(219,651)
Cash flows from financing activities:
Proceeds from bank borrowings	180,000
Repayments on bank borrowings	(35,000)
Distributions to Parent	(167,470)
Other	(2,069)
Net cash provided by (used in) financing activities	(24,539)
Increase (decrease) in cash	(21,193)
Cash and cash equivalents at beginning of period	31,768
Cash and cash equivalents at ending of period	10,575
Non-Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	1,251
Cash flows from investing activities:
Additions to oil and natural gas properties	(311)
Acquisitions, net of cash acquired	3,481
Proceeds from sale of available-for-sale securities	8,535
Purchases of available-for-sale securities	(10,249)
Net cash (used in) provided by investing activities	1,456
Cash flows from financing activities:
Increase (decrease) in cash	2,707
Cash and cash equivalents at ending of period	2,707
Eliminations [Member]
Cash flows from investing activities:
Distributions from subsidiaries	(167,470)
Net cash (used in) provided by investing activities	(167,470)
Cash flows from financing activities:
Distributions to Parent	167,470
Net cash provided by (used in) financing activities	$ 167,470