Fair Value of Financial Assets and Liabilities, Impact of Derivative Activity (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financial Impact of Qualifying Fair Value Hedges on Earnings [Abstract]
Derivative instruments designated as fair value hedges	$ 0	$ 0	$ 0	$ 0
Gain (Loss) on Fair Value Hedges Recognized in Earnings	0	0	0	0
Cash Flow Hedges | Interest Rate Contract
Impact of Derivative Activity on Accumulated Other Comprehensive Income (Loss) Regulatory Assets and Liabilities and Income [Abstract]
Pre-tax losses reclassified into income during the period from accumulated other comprehensive loss			(100,000)	(100,000)
Other Derivative Instruments | Natural Gas Commodity
Impact of Derivative Activity on Accumulated Other Comprehensive Income (Loss) Regulatory Assets and Liabilities and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory assets and liabilities		(200,000)	700,000	(400,000)
Pre-tax gains reclassified into income during the period from regulatory assets and liabilities			$ 500,000