Regulated Operating Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Regulated Operating Expense
Electric transmission and distribution expense	$ 4,108	$ 3,823	$ 15,647	$ 13,992
Natural gas transmission and distribution expense	652	562	2,476	2,225
Power operation expense (other than fuel)	3,794	2,677	14,394	11,129
Customer accounts & assistance expense	2,434	2,536	10,108	11,234
Employee pension expense	2,536	1,844	9,496	6,279
Employee healthcare plan	2,238	1,621	8,056	7,001
General office supplies and expense	2,752	2,898	10,011	11,807
Administrative and general expense	4,219	3,647	14,868	13,126
Allowance for uncollectible accounts	593	82	3,935	3,133
Miscellaneous expense	22	25	84	164
TOTAL	$ 23,348	$ 19,715	$ 89,075	$ 80,090