Litigation, Environmental and Other Contingencies (Details) (USD $)			12 Months Ended										12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009 County Treasurer of Montezuma County, Colorado [Member]	Dec. 31, 2009 County Treasurer of Montezuma County, Colorado [Member] Kinder Morgan CO2 [Member]	Dec. 31, 2012 PHMSA [Member]	Dec. 31, 2012 Exxon Mobil Corporation [Member]	Dec. 31, 2012 Federal Energy Regulatory Commission Proceedings [Member]	Dec. 31, 2012 California Public Utilities Commission Proceedings [Member]	Dec. 31, 2012 Carbon Dioxide Tax Assessments [Member] Colorado Department of Revenue [Member]	Dec. 31, 2012 Union Pacific Railroad Company Easements [Member]	Dec. 31, 2012 Severstal Sparrows Point Crane Collapse [Member]	Dec. 31, 2012 Perth Amboy, New Jersey Tank Release [Member]	Dec. 31, 2012 EPNG Docket No RP08-426 [Member]
Loss Contingencies [Line Items]
Estimated amount shippers are seeking in annual rate reductions							$ 20,000,000	$ 30,000,000
Loss contingency, damages sought, value						1,000,000	100,000,000	375,000,000		75,000,000	30,000,000
Loss contingency, settlement agreement, consideration							54,000,000
Loss contingency, pending claims, number (Notices)									3
Tax settlements range of possible loss									6,000,000
Interest from tax examination									1,000,000
Penalties from tax examination									2,000,000
Tax settlements			2,000,000
Percentage of additional property tax assessment				37.20%
Annual rent payable										15,000,000
Loss contingency, interest associated with settlement										20,000,000
Loss contingency, range of possible loss, maximum												1,000,000
Estimated litigation liability	310,000,000	332,000,000
Loss Contingency, Damages Paid, Value					118,500
Increase in revenues sought													$ 100,000,000
Rate reductions sought, percent								7.00%