Commitments and Contingencies (Details-1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 Columbia Units [Member]	Jun. 17, 2014 EPA [Member]
Public Utilities, General Disclosures [Line Items]
National average reduction of greenhouse gas emissions by the year 2030, percentage		30.00%
Columbia Commitments [Abstract]
Accrual for future environmental mitigation projects	$ 0.6
Envrionmental civil penalty expense	$ 0.2