Derivative and Hedging Instruments (Details-5) (USD $)			3 Months Ended									3 Months Ended
	Mar. 31, 2014 counterparty	Dec. 31, 2013 counterparty	Mar. 31, 2014 Commodity Derivative Contracts [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2013 Commodity Derivative Contracts [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2014 Commodity Derivative Contracts [Member] Cost Of Gas Sold Expense [Member]	Mar. 31, 2013 Commodity Derivative Contracts [Member] Cost Of Gas Sold Expense [Member]	Mar. 31, 2014 Financial Transmission Rights [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2013 Financial Transmission Rights [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2014 Financial Transmission Rights [Member] Cost Of Gas Sold Expense [Member]	Mar. 31, 2013 Financial Transmission Rights [Member] Cost Of Gas Sold Expense [Member]	Mar. 31, 2014 Purchased Power Agreement [Member]	Mar. 31, 2014 Purchased Power Agreement [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2013 Purchased Power Agreement [Member] Fuel For Electric Generation Purchased Power [Member]	Mar. 31, 2014 Purchased Power Agreement [Member] Cost Of Gas Sold Expense [Member]	Mar. 31, 2013 Purchased Power Agreement [Member] Cost Of Gas Sold Expense [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement			$ (4,795,000)	$ 22,000	$ (1,220,000)	$ 608,000	$ (636,000)	$ (158,000)	$ 0	$ 0		$ (1,210,000)	$ 1,278,000	$ 0	$ 0
Derivative collateral required to be posted for ten-year PPA [Abstract]
Minimum collateral that may be required to be posted											20,000,000
Maximum collateral that may be required to be posted											40,000,000
Collateral posted											$ 0
Counterparties in net liability position or default [Abstract]
Counterparties in net liability position	0	0
Number of counterparties in default	0