CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Utility plant:
Utility plant	$ 2,373,167	$ 2,342,471
Less accumulated depreciation and amortization	(766,545)	(752,040)
Net utility plant	1,606,622	1,590,431
Current assets:
Cash and cash equivalents	33,311	19,587
Receivables:
Customers	24,327	25,803
Regulatory balancing accounts	50,016	53,199
Other	13,349	14,136
Unbilled revenue	22,599	23,740
Materials and supplies at weighted average cost	6,158	6,041
Taxes, prepaid expenses and other assets	9,495	11,618
Total current assets	159,255	154,124
Other assets:
Regulatory assets	401,089	390,331
Goodwill	2,615	2,615
Other assets	51,164	49,850
Total other assets	454,868	442,796
Total assets	2,220,745	2,187,351
Capitalization:
Common stock, $.01 par value; 68,000 shares authorized, 47,880 and 47,806 outstanding in 2015 and 2014, respectively	479	478
Additional paid-in capital	331,029	330,558
Retained earnings	289,158	295,590
Total common stockholders' equity	620,666	626,626
Long-term debt, less current maturities	419,014	419,233
Total capitalization	1,039,680	1,045,859
Current liabilities:
Current maturities of long-term debt	6,596	6,607
Short-term borrowings	109,115	79,115
Accounts payable	57,684	59,395
Regulatory balancing accounts	5,580	6,126
Accrued interest	9,583	4,194
Accrued expenses and other liabilities	65,385	62,269
Total current liabilities	253,943	217,706
Unamortized investment tax credits	2,032	2,032
Deferred income taxes, net	214,814	214,842
Pension and postretirement benefits other than pensions	277,094	270,865
Regulatory and other liabilities	81,499	83,279
Advances for construction	181,553	182,284
Contributions in aid of construction	170,130	170,484
Commitments and contingencies (Note 10)
Total capitalization and liabilities	$ 2,220,745	$ 2,187,351