Derivative and Hedging Instruments (Details-3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Commodity Derivative Contracts [Member]
Offsetting Liabilities [Line Items]
Gross liability	$ 99	$ 405
Gross amounts offset in balance sheet	(99)	(405)
Collateral posted against derivative positions	0	0
Net amount presented in the balance sheet	0	0
Ten-year PPA [Member]
Offsetting Liabilities [Line Items]
Gross liability	65,680	72,590
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in the balance sheet	$ 65,680	$ 72,590