STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating revenues	$ 861,994	$ 903,603	$ 916,797
Operating expenses:
Fuel and purchased power	175,921	229,109	244,751
Operations and maintenance	332,557	334,883	320,281
Depreciation and amortization	102,072	96,382	90,843
Taxes other than income taxes	73,351	71,000	70,863
Utilities operating expense	683,901	731,374	726,738
Operating income	178,093	172,229	190,059
Other income (deductions):
Allowance for equity funds used during construction	2,545	3,453	3,025
Investment and interest income, net	69,627	18,377	38,853
Miscellaneous non-operating income	15,269	12,823	12,051
Strategic transaction costs	(12,110)	0	0
Miscellaneous non-operating deductions	(9,946)	(11,980)	(11,580)
Nonoperating income	65,385	22,673	42,349
Interest charges (credits):
Interest on long-term debt and revolving credit facility	74,788	75,424	72,970
Other interest	21,366	17,890	18,170
Capitalized interest	(5,729)	(5,483)	(5,022)
Allowance for borrowed funds used during construction	(4,015)	(3,612)	(2,975)
Interest expense	86,410	84,219	83,143
Income before income taxes	157,068	110,683	149,265
Income tax expense	34,031	26,368	51,004
Net income	$ 123,037	$ 84,315	$ 98,261
Basic earnings per share	$ 3.02	$ 2.070	$ 2.420
Diluted earnings per share	3.01	2.070	2.420
Dividends declared per share of common stock	$ 1.515	$ 1.415	$ 1.315
Weighted average number of shares outstanding	40,605,597	40,521,364	40,414,556
Weighted average number of shares and dilutive potential shares outstanding	40,681,221	40,642,640	40,535,191