Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2014
Minimum [Member]
Regulatory Liabilities [Line Items]
Same as cash, fee recognition period	3 months
Authorized contractor, fee recognition period	1 year
Maximum [Member]
Regulatory Liabilities [Line Items]
Financial incentive as percentage of energy optimization program spending	15.00%
Energy optimization spending limit	2.00%
Same as cash, fee recognition period	24 months
Authorized contractor, fee recognition period	12 years