Subsidiary Guarantors (Condensed Consolidated Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net cash (used in) 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) provided by investing activities	(113,130)	(41,238)
Cash flows from financing activities:
Distributions to unitholders	(70,964)	(70,752)
Proceeds from bank borrowings	100,000
Other	(2,000)
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
Parent Co - Issuer [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(14,566)
Cash flows from investing activities:
Distributions from subsidiaries	87,525
Net cash (used in) provided by investing activities	87,525
Cash flows from financing activities:
Distributions to unitholders	(70,964)
Other	(2,000)
Net cash provided by (used in) financing activities	(72,964)
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	92,612
Cash flows from investing activities:
Additions to oil and natural gas properties	(72,164)
Acquisitions	(40,434)
Net cash (used in) provided by investing activities	(112,598)
Cash flows from financing activities:
Proceeds from bank borrowings	100,000
Distributions to Parent	(87,525)
Net cash provided by (used in) financing activities	12,475
Increase (decrease) in cash	(7,511)
Cash and cash equivalents at beginning of period	10,575
Cash and cash equivalents at ending of period	3,064
Non-Guarantor [Member]
Cash flows from operating activities:
Net cash (used in) provided by operating activities	1,103
Cash flows from investing activities:
Additions to oil and natural gas properties	(989)
Proceeds from sale of available-for-sale securities	893
Purchases of available-for-sale securities	(436)
Net cash (used in) provided by investing activities	(532)
Cash flows from financing activities:
Increase (decrease) in cash	571
Cash and cash equivalents at beginning of period	2,707
Cash and cash equivalents at ending of period	3,278
Eliminations [Member]
Cash flows from investing activities:
Distributions from subsidiaries	(87,525)
Net cash (used in) provided by investing activities	(87,525)
Cash flows from financing activities:
Distributions to Parent	87,525
Net cash provided by (used in) financing activities	$ 87,525