Commitments and Contingencies (Details) (USD $)	Dec. 31, 2011
Commitments and Contingencies (Details) [Abstract]
Pipeline Financing Leases in Year 1	$ 30,689,000
Pipeline Financing Leases in Year 2	32,469,000
Pipeline Financing Leases in Year 3	34,036,000
Pipeline Financing Leases in Year 4	31,847,000
Pipeline Financing Leases in Year 5	30,912,000
Pipeline Financing Leases, Thereafter	344,233,000
Pipeline financing leases, Total minimum lease payments	504,186,000
Pipeline Financing Leases, Less: Amount representing interest	260,912,000
Present Value Of Future Minimum Lease Payments Sale Leaseback Transactions	243,274,000
Capital Leases in Year 1	2,206,000
Capital Leases in Year 2	1,447,000
Capital Leases in Year 3	664,000
Capital Leases in Year 4	106,000
Capital Leases in Year 5	106,000
Capital Leases, Thereafter	510,000
Capital Leases Total minimum lease payments	5,039,000
Capital leases, Less: Amount representing interest	(651,000)
Capital leases, Present value of minimum lease payments	4,388,000
Operating Leases in Year 1	36,207,000
Operating Leases in Year 2	37,509,000
Operating Leases in Year 3	34,369,000
Operating Leases in Year 4	33,536,000
Operating Leases in Year 5	31,349,000
Operating Leases, Thereafter	74,269,000
Operating Leases, Total minimum lease payments	$ 247,239,000