Disclosures About Fair Value Measurements (Fair Value Measurements Using Significant Unobservable Inputs) (Details) (NGL Swap Contracts [Member], USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011		Jun. 30, 2011
NGL Swap Contracts [Member]
Beginning liability balance	$ (16,675)		$ (9,556)
Net unrealized gains (losses) included in earnings	3,324	[1]	(3,795)	[1]
Net realized losses included in earnings	(4,629)	[1]	(7,325)	[1]
Settlement payments	4,629		7,325
Ending liability balance	$ (13,351)		$ (13,351)

[1] Non-hedge derivatives gains and losses are included in net derivative (gains) losses in the accompanying consolidated statements of operations.