CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Utility plant:
Utility plant	$ 2,236,187	$ 2,213,328
Less accumulated depreciation and amortization	(713,069)	(697,497)
Net utility plant	1,523,118	1,515,831
Current assets:
Cash and cash equivalents	21,744	27,506
Receivables:
Customers	26,799	31,468
Regulatory balancing accounts	28,547	30,887
Other	19,878	18,700
Unbilled revenue	14,594	17,034
Materials and supplies at weighted average cost	5,966	5,571
Taxes, prepaid expenses and other assets	12,578	8,324
Total current assets	130,106	139,490
Other assets:
Regulatory assets	254,345	251,681
Goodwill	2,615	2,615
Other assets	52,404	50,238
Total other assets	309,364	304,534
Total assets	1,962,588	1,959,855
Capitalization:
Common stock, $.01 par value; 68,000,000 shares authorized, 47,804,000 and 47,741,000 outstanding in 2014 and 2013, respectively	478	477
Additional paid-in capital	328,826	328,364
Retained earnings	256,680	269,915
Total common stockholders' equity	585,984	598,756
Long-term debt, less current maturities	425,730	426,142
Total capitalization	1,011,714	1,024,898
Current liabilities:
Current maturities of long-term debt	7,860	7,908
Short-term borrowings	64,015	46,815
Accounts payable	50,731	55,087
Regulatory balancing accounts	6,130	1,827
Accrued interest	9,828	4,245
Accrued expenses and other liabilities	53,675	50,702
Total current liabilities	192,239	166,584
Unamortized investment tax credits	2,106	2,106
Deferred income taxes, net	179,369	183,245
Pension and postretirement benefits other than pensions	145,836	145,451
Regulatory and other liabilities	81,699	86,455
Advances for construction	182,042	183,393
Contributions in aid of construction	167,583	167,723
Commitments and contingencies (Note 10)
Total capitalization and liabilities	$ 1,962,588	$ 1,959,855