Fair Value (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Commodity contracts (net)
Derivative assets and liabilities classified by the Partnership within Level 3 of the valuation hierarchy
Fair value at beginning of period	$ 12,477	$ (17,450)	$ 12,449	$ (2,965)
Total gain (realized and unrealized) included in earnings	16,896	46,290	20,220	34,214
Settlements	(2,995)	716	(6,291)	(1,693)
Fair value at end of period	26,378	29,556	26,378	29,556
The amount of total net 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	14,755	43,894	17,854	30,304
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	(24,881)	(60,804)	(33,957)	(53,904)
Total gain (realized and unrealized) included in earnings	20,459	48,109	26,991	37,671
Settlements	2,019	2,300	4,563	5,838
Fair value at end of period	(2,403)	(10,395)	(2,403)	(10,395)
The amount of total net 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	$ 20,766	$ 47,300	$ 27,229	$ 36,698