Significant Accounting Policies (Other Policies) (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Asset Retirement Obligation [Abstract]
Asset Retirement Obligation, Current	$ 500,000	$ 500,000
Acquired Finite-Lived Intangible Assets [Line Items]
Hedging gains or losses reclassified to earnings	1,002,000	641,000	(1,769,000)
Goodwill	153,802,000	152,627,000
Gas Balancing Payable, Current	4,800,000	2,300,000
Gas Balancing Asset (Liability)	4,235,000	1,533,000
Other Assets, Noncurrent [Abstract]
New Date of Annual Goodwill Impairment Test	July 1, 2013
Deferred Finance Costs, Noncurrent, Net	$ 22,800,000	$ 26,000,000