Significant Risks and Uncertainties (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Insurance Matters [Abstract]
Minimum insurance deductible per incident	$ 5.0
Maximum insurance deductible per incident	75.0
Schedule of Gains Recognized From Business Insurance Recoveries [Line Items]
Total gains recognized	4.3		1.1		33.2
Loss Contingencies [Line Items]
Gains (losses) from asset sales and related transactions	155.7		46.7		0
Gains related to property damage proceeds			26.4		12.4
February 2011 West Storage Incident [Member]
Loss Contingencies [Line Items]
Estimate of cost related to incident	150
December 2011 Falcon Compressor Station Incident [Member]
Loss Contingencies [Line Items]
Gains (losses) from asset sales and related transactions	(5.3)
Insurance claims outstanding	15
NGL Pipelines & Services [Member]
Schedule of Gains Recognized From Business Insurance Recoveries [Line Items]
Total gains recognized	4.3		0		4.3
Offshore Pipelines & Services [Member]
Schedule of Gains Recognized From Business Insurance Recoveries [Line Items]
Total gains recognized	$ 0	[1]	$ 1.1	[1]	$ 28.9	[1]

[1] Gains recognized within this segment pertain to business interruption proceeds from hurricane claims in 2005 and 2008.