CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING ACTIVITIES:
Net Income	$ 224,111	$ 194,131	$ 183,008
Adjustments to reconcile net income to cash provided by operations:
Depreciation and depletion	227,635	210,474	195,020
Amortization of debt issuance costs, discount and deferred hedge gain	4,647	5,142	5,321
Stock-based compensation costs	4,721	5,176	5,488
Equity portion of AFUDC	(18,628)	(17,614)	(14,191)
(Gain) loss on disposition of assets	(61)	316	482
Deferred income taxes	(8,969)	6,584	(8,992)
Changes in current assets and liabilities:
Accounts receivable	24,493	32,695	(46,282)
Inventories	(8,402)	(7,180)	(26,744)
Other current assets	(13,216)	2,644	(3,833)
Accounts payable	7,399	(54,722)	50,537
Accrued expenses	9,748	(3,377)	16,846
Regulatory assets	(10,109)	105,588	(20,512)
Regulatory liabilities	(28,842)	39,957	(7,034)
Other noncurrent assets and liabilities	(11,945)	(30,583)	(21,872)
Cash Provided by Operating Activities	406,741	489,231	307,242
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(549,244)	(566,889)	(515,140)
Investment in equity securities	(4,719)	(3,923)	(1,719)
Payments for (Proceeds from) Other Investing Activities	(500)	0	0
Cash Used in Investing Activities	(554,463)	(570,812)	(516,859)
FINANCING ACTIVITIES:
Dividends on common stock	(158,589)	(154,050)	(140,062)
Proceeds from issuance of common stock, net	0	73,613	276,971
Issuance of long-term debt	215,000	300,000	0
Payment for Debt Extinguishment or Debt Prepayment Cost	(100,000)	0	0
Line of credit borrowings (repayments), net	95,000	(132,000)	77,000
Issuances of short-term borrowings	100,000	0	0
Treasury stock activity	1,192	1,069	603
Financing costs	(1,051)	(4,327)	(1,194)
Cash Provided by Financing Activities	151,552	84,305	213,318
Net Increase in Cash, Cash Equivalents, and Restricted Cash	3,830	2,724	3,701
Cash, Cash Equivalents, and Restricted Cash, beginning of period	25,187	22,463	18,762
Cash, Cash Equivalents, and Restricted Cash, end of period	29,017	25,187	22,463
Other Noncash Expense	$ 4,159	$ 0	$ 0