Derivative and Hedging Instruments (Details-1) (USD $) In Thousands, unless otherwise specified							3 Months Ended	12 Months Ended									3 Months Ended		12 Months Ended
	Mar. 31, 2014 Other Current Assets [Member]	Dec. 31, 2013 Other Current Assets [Member]	Mar. 31, 2013 Other Current Assets [Member]	Dec. 31, 2012 Other Current Assets [Member]	Mar. 31, 2014 Commodity Contracts And Financial Transimission Rights [Member]	Dec. 31, 2013 Commodity Contracts And Financial Transimission Rights [Member]	Mar. 31, 2014 Commodity Derivative Contracts [Member] MWh Dth	Dec. 31, 2013 Commodity Derivative Contracts [Member] MWh Dth	Mar. 31, 2014 Commodity Derivative Contracts [Member] Other Current Assets [Member]	Dec. 31, 2013 Commodity Derivative Contracts [Member] Other Current Assets [Member]	Mar. 31, 2014 Commodity Derivative Contracts [Member] Other Deferred Charges [Member]	Dec. 31, 2013 Commodity Derivative Contracts [Member] Other Deferred Charges [Member]	Mar. 31, 2014 Commodity Derivative Contracts [Member] Derivative Liability (Current) [Member]	Dec. 31, 2013 Commodity Derivative Contracts [Member] Derivative Liability (Current) [Member]	Mar. 31, 2014 Commodity Derivative Contracts [Member] Derivative Liability (Long-term) [Member]	Dec. 31, 2013 Commodity Derivative Contracts [Member] Derivative Liability (Long-term) [Member]	Mar. 31, 2014 Energy Related Commodity Contract [Member] Cash Flow Hedging [Member]	Mar. 31, 2014 Financial Transmission Rights [Member] MW	Dec. 31, 2013 Financial Transmission Rights [Member] MW	Mar. 31, 2014 Financial Transmission Rights [Member] Other Current Assets [Member]	Dec. 31, 2013 Financial Transmission Rights [Member] Other Current Assets [Member]	Mar. 31, 2014 Financial Transmission Rights [Member] Derivative Liability (Current) [Member]	Dec. 31, 2013 Financial Transmission Rights [Member] Derivative Liability (Current) [Member]	Mar. 31, 2014 Ten-year PPA [Member]	Dec. 31, 2013 Ten-year PPA [Member]	Mar. 31, 2014 Ten-year PPA [Member] Derivative Liability (Current) [Member]	Dec. 31, 2013 Ten-year PPA [Member] Derivative Liability (Current) [Member]	Mar. 31, 2014 Ten-year PPA [Member] Derivative Liability (Long-term) [Member]	Dec. 31, 2013 Ten-year PPA [Member] Derivative Liability (Long-term) [Member]
Derivatives Fair Value [Line Items]
Maximum term of derivative hedging contract																	4 years
Gross Notional Volume of Open Derivatives
Notional amount, energy measure (in MWh)							409,800	458,660
Notional amount, decatherm measure (in Dth)							2,200,000	3,750,000
Notional amount, power measure (in MW)																		790	1,984
Derivative fair values [Abstract]
Derivative fair value, net	$ 351	$ 411	$ 259	$ 574	$ 2,100	$ 1,800																		$ (60,300)	$ (65,700)
Derivative Asset, Fair Value, Gross Asset							2,123	1,523	2,086	1,356	37	167						106	363	106	363
Derivative Liability, Fair Value, Gross Liability							$ 152	$ 99					$ 111	$ 51	$ 41	$ 48						$ 0	$ 0	$ 60,290	$ 65,680	$ 6,540	$ 7,750	$ 53,750	$ 57,930