Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 33,943	$ 77,814
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	85,496	75,941
Accretion of asset retirement obligations	5,411	4,109
Recognition of unit-based awards	5,120	2,124
General and administrative expense contributed by affiliates		26,785
Loss (gain) on derivative contracts, net	14,414	(41,909)
Cash received (paid) on settlement of derivative contracts	13,093	14,893
Other items	3,445	4,073
Changes in operating assets and liabilities:
Accounts receivable and other assets	(20,716)	(11,232)
Accounts payable and other liabilities	1,612	5,359
Net cash provided by operating activities	141,818	157,957
Cash flows from investing activities:
Additions to oil and gas properties	(65,898)	(100,940)
Acquistions, net of cash acquired	(101,696)	(225,118)
Proceeds from the sale of oil and gas properties		3,082
Proceeds from sale of available-for-sale securities	4,643
Purchases of available-for-sale securities	(4,268)
Net cash used in investing activities	(167,219)	(322,976)
Cash flows from financing activities:
Proceeds from senior note offering, net of discount		295,860
Proceeds from issuance of units to the General Partner		115
Proceeds from issuance of units	87	161,958
Management incentive fee to the General Partner	(2,014)	(3,155)
Distributions to unitholders	(106,226)	(70,959)
Distributions to the Predecessor		(27,177)
Proceeds from bank borrowings	150,000	116,500
Repayments on bank borrowings	(20,000)	(291,500)
Deferred financing costs	(1,828)	(8,891)
Other	(390)	(21)
Net cash provided by (used in) financing activities	19,629	172,730
Increase (decrease) in cash	(5,772)	7,711
Cash and Cash Equivalents, at Carrying Value, Beginning Balance	31,836	17,433
Cash and Cash Equivalents, at Carrying Value, Ending Balance	$ 26,064	$ 25,144