Commitments and Contingencies (Details-2) (USD $)	9 Months Ended
	Sep. 30, 2012
Chattel Paper Purchase Agreement [Abstract]
Chattel paper purchase agreement maximum interest	$ 10,000,000
Outstanding interest in chattel paper receivables	3,900,000
Servicing asset recognized	200,000
Smart Grid Investment Grant [Abstract]
Smart Grid grant approval amount	5,500,000
Total cost of proposed projects	11,000,000
Smart grid expenditures to date	7,900,000
Investment Capital Contribution Commitment [Abstract]
Capital contribution commitment	2,000,000
One Year From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	126,000
Operating expense purchase contracts [Abstract]
Coal commitments	2,483,000
Natural Gas Commitments [Abstract]
Natural gas supply commitments	12,872,000
Purchase power commitments	39,266,000
Total purchase contracts	54,621,000
Smart Grid Investment Grant [Abstract]
Smart grid commitments to date	600,000
More Than One And Within Two Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	669,000
Operating expense purchase contracts [Abstract]
Coal commitments	21,884,000
Natural Gas Commitments [Abstract]
Natural gas supply commitments	13,192,000
Purchase power commitments	51,455,000
Total purchase contracts	86,531,000
Smart Grid Investment Grant [Abstract]
Smart grid commitments to date	1,300,000
More Than Two And Within Three Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	484,000
Operating expense purchase contracts [Abstract]
Coal commitments	9,459,000
Natural Gas Commitments [Abstract]
Natural gas supply commitments	0
Purchase power commitments	49,372,000
Total purchase contracts	58,831,000
More Than Three And Within Four Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	796,000
Operating expense purchase contracts [Abstract]
Coal commitments	6,340,000
Natural Gas Commitments [Abstract]
Natural gas supply commitments	0
Purchase power commitments	47,523,000
Total purchase contracts	53,863,000
More Than Four And Within Five Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	721,000
Operating expense purchase contracts [Abstract]
Coal commitments	1,623,000
Natural Gas Commitments [Abstract]
Natural gas supply commitments	0
Purchase power commitments	48,491,000
Total purchase contracts	$ 50,114,000