Derivative Instruments (Detail Effect Of Derivative Assets And Liabilities In Statement Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivatives in cash flow hedging relationship [Member] | Commodity derivatives [Member]
Change in value recognized in AOCI on derivatives (effective portion)	$ 0	$ 1,530	$ 0	$ (15,466)
Derivatives in cash flow hedging relationship [Member] | Commodity derivatives [Member] | Revenues [Member]
Amount of gain (loss) reclassified from AOCI into income (effective portion)	0	(7,133)	0	(8,994)
Amount of gain (loss) recognized in income on ineffective portion	0	(362)	0	(274)
Derivatives not designated in a hedging relationships [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	25,055	2,675	28,020	5,050
Derivatives not designated in a hedging relationships [Member] | Commodity derivatives [Member] | Revenues [Member]
Amount of gain (loss) from designation amortized from AOCI into income	(2,159)	0	(5,824)	0
Derivative Instruments, Gain (Loss) Recognized in Income, Net	17,146	(47)	19,627	12
Derivatives not designated in a hedging relationships [Member] | Interest rate swap contracts [Member] | Interest Expense, Net [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	0	(228)	(12)	(487)
Derivatives not designated in a hedging relationships [Member] | Embedded derivatives in Series A Preferred Units [Member] | Other Income and Deductions, Net [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 7,909	$ 2,950	$ 8,405	$ 5,525