Intangible Assets (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Intangible Assets
Intangible assets, net	$ 186,872,000		$ 186,872,000		$ 188,585,000
Intangible Assets (Textuals) [Abstract]
Weighted average amortization period			19	20
Additional Intangible Assets (Textuals) [Abstract]
Amortization Expenses	2,956,000	2,782,000	5,854,000	5,562,000
Aggregate amortization expense, 2011			5,920,000
Aggregate amortization expense, 2012			11,916,000
Aggregate amortization expense, 2013			11,742,000
Aggregate amortization expense, 2014			11,464,000
Aggregate amortization expense, 2015			11,403,000
Aggregate amortization expense, 2016			11,384,000
Rights-of-way and easements [Member]
Intangible Assets
Gross	129,137,000		129,137,000		125,496,000
Less accumulated amortization	(26,007,000)		(26,007,000)		(23,234,000)
Intangible Assets (Textuals) [Abstract]
Weighted average amortization period			20	22
Contracts [Member]
Intangible Assets
Gross	108,416,000		108,416,000		107,916,000
Less accumulated amortization	(28,078,000)		(28,078,000)		(25,153,000)
Intangible Assets (Textuals) [Abstract]
Weighted average amortization period			18	18
Customer relationships [Member]
Intangible Assets
Gross	4,864,000		4,864,000		4,864,000
Less accumulated amortization	$ (1,460,000)		$ (1,460,000)		$ (1,304,000)
Intangible Assets (Textuals) [Abstract]
Weighted average amortization period			11	12