Fair Value (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commodity Derivative Contracts (net)
Derivative assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy
Fair value at beginning of period	$ 26,378	$ 29,556	$ 12,449	$ (2,965)
Total (loss) gain (realized and unrealized) included in earnings	(24,269)	(13,199)	(4,050)	21,016
Settlements	834	415	(5,456)	(1,279)
Fair value at end of period	2,943	16,772	2,943	16,772
The amount of total (losses) gains for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period	(20,250)	(11,754)	(5,656)	14,843
Embedded Derivatives in Commodity Contracts (net)
Derivative assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy
Fair value at beginning of period	(2,403)	(10,395)	(33,957)	(53,904)
Total (loss) gain (realized and unrealized) included in earnings	(24,786)	(19,842)	2,206	17,829
Settlements	2,085	2,262	6,647	8,100
Fair value at end of period	(25,104)	(27,975)	(25,104)	(27,975)
The amount of total (losses) gains for the period included in earnings attributable to the change in unrealized gains or losses relating to contracts still held at end of period	$ (22,742)	$ (15,643)	$ 3,883	$ 17,728