Subsidiary Guarantors (Condensed Consolidated Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net cash (used in) 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) provided by investing activities	(58,424)	(16,230)
Cash flows from financing activities:
Distributions to unitholders	(35,422)	(32,284)
Proceeds from bank borrowings	63,000
Other	(1,424)	121
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
Parent Co - Issuer [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(15,083)
Cash flows from investing activities:
Distributions from subsidiaries	51,924
Net cash (used in) provided by investing activities	51,924
Cash flows from financing activities:
Distributions to unitholders	(35,422)
Other	(1,424)
Net cash provided by (used in) financing activities	(36,846)
Increase (decrease) in cash	(5)
Cash and cash equivalents at beginning of period	78
Cash and cash equivalents at ending of period	73
Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	57,589
Cash flows from investing activities:
Additions to oil and natural gas properties	(29,107)
Acquisitions	(29,016)
Net cash (used in) provided by investing activities	(58,123)
Cash flows from financing activities:
Proceeds from bank borrowings	63,000
Distributions to Parent	(51,924)
Net cash provided by (used in) financing activities	11,076
Increase (decrease) in cash	10,542
Cash and cash equivalents at beginning of period	10,575
Cash and cash equivalents at ending of period	21,117
Non-Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(336)
Cash flows from investing activities:
Additions to oil and natural gas properties	(726)
Proceeds from sale of available-for-sale securities	614
Purchases of available-for-sale securities	(189)
Net cash (used in) provided by investing activities	(301)
Cash flows from financing activities:
Increase (decrease) in cash	(637)
Cash and cash equivalents at beginning of period	2,707
Cash and cash equivalents at ending of period	2,070
Eliminations [Member]
Cash flows from investing activities:
Distributions from subsidiaries	(51,924)
Net cash (used in) provided by investing activities	(51,924)
Cash flows from financing activities:
Distributions to Parent	51,924
Net cash provided by (used in) financing activities	$ 51,924