Regulated Operating Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Regulated Operating Expense
Electric transmission and distribution expense	$ 6,798	$ 5,028	$ 23,633	$ 18,003
Natural gas transmission and distribution expense	675	546	2,627	2,337
Power operation expense (other than fuel)	3,991	3,644	15,989	15,042
Customer accounts and assistance expense	2,836	2,579	11,436	10,356
Employee pension expense	2,626	2,643	10,720	10,287
Employee healthcare plan	1,725	2,786	9,128	10,374
General office supplies and expense	4,191	3,429	13,613	11,453
Administrative and general expense	4,225	4,315	14,710	15,187
Allowance for uncollectible accounts	773	746	3,692	3,191
Regulatory reversal of gain on sale of assets	0	1,236	0	1,236
Miscellaneous expense	117	185	605	694
Total	$ 27,957	$ 27,137	$ 106,153	$ 98,160