CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Utility plant:
Utility plant	$ 2,160,706	$ 2,096,363
Less accumulated depreciation and amortization	(670,452)	(639,307)
Net utility plant	1,490,254	1,457,056
Current assets:
Cash and cash equivalents	38,668	38,790
Receivables: net of allowance for doubtful accounts of $714 for both periods presented
Customers	41,493	29,958
Regulatory balancing accounts	25,560	34,020
Other	14,335	11,943
Unbilled revenue	24,750	15,394
Materials and supplies at weighted average cost	5,720	5,874
Taxes, prepaid expenses and other assets	13,550	10,585
Total current assets	164,076	146,564
Other assets:
Regulatory assets	353,910	344,419
Goodwill	2,615	2,615
Other assets	47,752	45,270
Total other assets	404,277	392,304
Total assets	2,058,607	1,995,924
Capitalization:
Common stock, $.01 par value; 68,000,000 shares authorized, 47,734,035 and 41,908,218 outstanding in 2013 and 2012, respectively	477	419
Additional paid-in capital	327,628	221,013
Retained earnings	250,375	252,280
Total common stockholders' equity	578,480	473,712
Long-term debt, less current maturities	430,705	434,467
Total capitalization	1,009,185	908,179
Current liabilities:
Current maturities of long-term debt	48,040	46,783
Short-term borrowings	28,815	89,475
Accounts payable	57,158	47,199
Regulatory balancing accounts	4,717	5,018
Accrued interest	4,608	4,705
Accrued expenses and other liabilities	52,872	49,887
Total current liabilities	196,210	243,067
Unamortized investment tax credits	2,180	2,180
Deferred income taxes, net	167,611	158,846
Pension and postretirement benefits other than pensions	248,003	244,901
Regulatory and other liabilities	88,578	92,593
Advances for construction	186,202	187,584
Contributions in aid of construction	160,638	158,574
Commitments and contingencies
Total capitalization and liabilities	$ 2,058,607	$ 1,995,924