CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 1,443	$ 1,571
Accounts receivable, net	46,488	51,838
Accrued unbilled revenues	34,484	48,668
Inventories	17,817	25,703
Regulatory assets	11,357	14,133
Prepaid taxes	15,814	21,841
Deferred income taxes	6,136	0
Prepayments and other	2,623	2,991
Total current assets	136,162	166,745
Property, plant and equipment, net	1,223,762	1,207,698
Other assets
Regulatory assets	230,364	229,910
Other investments	3,114	4,148
Other	3,127	2,970
Total other assets	236,605	237,028
Total assets	1,596,529	1,611,471
Current liabilities
Current portion of long-term debt	1,276	1,286
Short-term debt	71,000	66,000
Notes payable to affiliates	550	500
Accounts payable	21,642	30,897
Accounts payable to affiliates	24,175	23,285
Dividends payable to parent	0	8,107
Regulatory liabilities	6,807	16,609
Environmental liabilities	31,003	30,699
Taxes accrued	3,973	1,238
Accrued interest	5,549	6,521
Derivative instruments	0	2,514
Other	9,410	10,155
Total current liabilities	175,385	197,811
Deferred credits and other liabilities
Deferred income taxes	246,292	234,222
Deferred investment tax credits	8,642	8,499
Regulatory liabilities	120,270	119,187
Environmental liabilities	79,446	79,399
Customer advances	16,045	15,765
Pension and employee benefit obligations	47,752	60,328
Other	6,662	7,024
Total deferred credits and other liabilities	525,109	524,424
Commitments and contingencies
Capitalization
Long-term debt	368,104	368,083
Common stock - 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at March 31, 2012 and Dec. 31, 2011, respectively	93,300	93,300
Additional paid in capital	187,071	187,071
Retained earnings	248,055	241,296
Accumulated other comprehensive loss	(495)	(514)
Total common stockholder's equity	527,931	521,153
Total liabilities and equity	$ 1,596,529	$ 1,611,471