Related Party Transactions (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2011 Quarters	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Affiliated Entity [Member]	Dec. 31, 2011 Affiliated Entity [Member]	Dec. 31, 2010 Affiliated Entity [Member]	Dec. 31, 2009 Affiliated Entity [Member]	Dec. 31, 2011 Annual Administrative Fee [Member] Affiliated Entity [Member]	Dec. 31, 2010 Annual Administrative Fee [Member] Affiliated Entity [Member]	Dec. 31, 2009 Annual Administrative Fee [Member] Affiliated Entity [Member]	Dec. 31, 2011 Reimbursements Paid [Member] Affiliated Entity [Member]	Dec. 31, 2010 Reimbursements Paid [Member] Affiliated Entity [Member]	Dec. 31, 2009 Reimbursements Paid [Member] Affiliated Entity [Member]	Dec. 31, 2011 Shortfall Payments [Member] Affiliated Entity [Member]	Dec. 31, 2010 Shortfall Payments [Member] Affiliated Entity [Member]	Dec. 31, 2009 Shortfall Payments [Member] Affiliated Entity [Member]	Dec. 31, 2011 Proceeds From Reimbursements Received [Member] Affiliated Entity [Member]	Dec. 31, 2010 Proceeds From Reimbursements Received [Member] Affiliated Entity [Member]	Dec. 31, 2009 Proceeds From Reimbursements Received [Member] Affiliated Entity [Member]	Dec. 31, 2011 SLC Pipeline [Member]	Mar. 01, 2009 SLC Pipeline [Member]	Mar. 31, 2009 SLC Pipeline [Member] Affiliated Entity [Member]	Mar. 01, 2009 SLC Pipeline [Member] Finder's Fee [Member] Affiliated Entity [Member]	Mar. 01, 2009 Finder's Fee [Member] SLC Pipeline [Member]
Related Party Transaction [Line Items]
Minimum Annualized Payments Receivable				$ 192,000,000	$ 192,000,000
Related Party Transaction, Other Revenues from Transactions with Related Party				5,500,000
Annual Administrative Fee, Related Party								2,300,000	2,300,000	2,300,000
Revenue from Related Parties	167,626,000	146,376,000	101,395,000		167,600,000	146,400,000	101,400,000							3,300,000	3,600,000	2,400,000
Related Party Transaction, Reimbursements											21,400,000	18,600,000	17,000,000				11,900,000	3,700,000	1,700,000
Equity Method Investment, Aggregate Cost																					28,000,000		2,500,000	2,500,000
Noncontrolling Interest, Ownership Percentage by Parent																				25.00%	25.00%	25.00%
Distributions, Common Units, Cash	91,506,000	84,426,000	61,188,000		40,600,000	35,900,000	29,500,000
Due from Related Parties, Current				31,000,000	31,000,000	19,000,000
Due to Related Parties, Current				5,300,000	5,300,000	3,900,000
Deferred Revenue, Related Party														$ 4,000,000	$ 3,300,000
Installment Billings to Affiliate for Certain Past Deliveries on Crude Pipeline System, Period	6