Commitments and Contingencies (Details-2) (USD $)	3 Months Ended
	Mar. 31, 2013
Chattel Paper Purchase Agreement [Abstract]
Chattel paper purchase agreement maximum interest	$ 10,000,000
Outstanding interest in chattel paper receivables	4,300,000
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	9,600,000
One Year From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	531,000
Operating expense purchase contracts [Abstract]
Coal commitments	16,922,000
Purchase power commitments	49,182,000
Other commitments	1,939,000
Total purchase contracts	68,043,000
Smart Grid Investment Grant [Abstract]
Smart grid commitments to date	900,000
More Than One And Within Two Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	554,000
Operating expense purchase contracts [Abstract]
Coal commitments	9,933,000
Purchase power commitments	48,425,000
Other commitments	0
Total purchase contracts	58,358,000
More Than Two And Within Three Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	867,000
Operating expense purchase contracts [Abstract]
Coal commitments	9,252,000
Purchase power commitments	47,293,000
Other commitments	0
Total purchase contracts	56,545,000
More Than Three And Within Four Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	791,000
Operating expense purchase contracts [Abstract]
Coal commitments	1,623,000
Purchase power commitments	48,121,000
Other commitments	0
Total purchase contracts	49,744,000
More Than Four And Within Five Years From Balance Sheet Date [Member]
Chattel Paper Agreement Principal Payments [Abstract]
Chattel paper agreement principal payments commitments	382,000
Operating expense purchase contracts [Abstract]
Coal commitments	1,040,000
Purchase power commitments	49,242,000
Other commitments	0
Total purchase contracts	$ 50,282,000