Statements Of Operations - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Operating revenues	$ 158,563	$ 174,363	$ 846,194	$ 902,253
Operating expenses:
Fuel and purchased power	33,624	48,326	161,219	225,247
Operations and maintenance	80,704	80,413	332,848	335,136
Depreciation and amortization	26,466	25,126	103,412	97,694
Taxes other than income taxes	16,071	16,189	73,233	71,682
Utilities operating expense	156,865	170,054	670,712	729,759
Operating income	1,698	4,309	175,482	172,494
Other income (deductions):
Allowance for equity funds used during construction	586	1,001	2,130	3,534
Investment and interest income, net	(25,599)	23,707	20,321	36,929
Miscellaneous non-operating income	2,945	3,048	15,166	12,735
Strategic transaction costs	(1,295)	0	(13,405)	0
Miscellaneous non-operating deductions	(3,149)	(2,357)	(10,738)	(11,594)
Nonoperating income	(26,512)	25,399	13,474	41,604
Interest charges (credits):
Interest on long-term debt and revolving credit facility	18,743	18,989	74,542	76,425
Other interest	4,547	5,233	20,680	18,469
Capitalized interest	(1,378)	(1,532)	(5,575)	(5,801)
Allowance for borrowed funds used during construction	(885)	(972)	(3,928)	(3,686)
Interest expense	21,027	21,718	85,719	85,407
Income (loss) before income taxes	(45,841)	7,990	103,237	128,691
Income tax expense (benefit)	(10,632)	1,901	21,498	31,321
Net income (loss)	$ (35,209)	$ 6,089	$ 81,739	$ 97,370
Basic earnings (loss) per share	$ (0.870)	$ 0.15	$ 2.01	$ 2.39
Diluted earnings (loss) per share	(0.870)	0.15	2.00	2.39
Dividends declared per share of common stock	$ 0.385	$ 0.360	$ 1.540	$ 1.440
Weighted average number of shares outstanding	40,653,326	40,582,936	40,623,151	40,543,986
Weighted average number of shares and dilutive potential shares outstanding	40,653,326	40,663,753	40,691,961	40,661,228