Summary Of Significant Accounting Policies (Schedule Of Segment's Revenues) (Details)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
QEP Resources, Inc.[Member]
Revenue, Major Customer [Line Items]
Segment's revenues	22.00%	28.00%	35.00%
Valero Energy Corporation [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	18.00%	7.00%	5.00%
Sunoco Partners Marketing [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	10.00%	8.00%	7.00%
ONEOK [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	54.00%	53.00%	52.00%
Gavilon LLC [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	19.00%	12.00%	0.00%
ConocoPhillips [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	7.00%	12.00%	15.00%
Tenaska [Member]
Revenue, Major Customer [Line Items]
Segment's revenues	1.00%	7.00%	17.00%