Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Operating Activities:
Net income	$ 155,787	$ 138,112
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	123,556	111,037
Deferred income taxes and investment tax credits	(45,251)	(32,353)
Changes in regulatory assets and liabilities	100,003	84,333
Pension and postretirement benefit plan expense	22,608	22,787
Contributions to pension and postretirement benefit plans	(2,864)	(2,616)
Earnings of unconsolidated equity-method investments	(2,024)	(1,902)
Distributions from equity-method investments	950	0
Allowance for equity funds used during construction	(29,608)	(24,431)
Other non-cash adjustments to net income, net	5,238	2,896
Change in:
Accounts receivable and unbilled revenues	(28,617)	(24,211)
Prepayments	8,428	(2,624)
Materials, supplies, and fuel stock	(4,803)	(39,562)
Accounts and wages payable	(47,396)	(43,666)
Taxes accrued/receivable	37,508	37,039
Other assets and liabilities	7,713	31,208
Net cash provided by operating activities	301,228	256,047
Investing Activities:
Additions to property, plant and equipment, net	(534,629)	(605,902)
Payments received from transmission project joint funding partners	62,022	39,912
Other	(1,089)	7,573
Net cash used in investing activities	(473,696)	(558,417)
Financing Activities:
Issuance of long-term debt	400,000	0
Discount on issuance of long-term debt	(3,072)	0
Retirement of long-term debt	(19,885)	0
Payments on finance lease liabilities	(729)	0
Dividends on common stock	(93,461)	(84,886)
Issuance of Common Stock	3,054	233,178
Tax withholdings on net settlements of share-based awards	(3,294)	(3,694)
Other	(4,522)	(98)
Net cash provided by financing activities	278,091	144,500
Net increase (decrease) in cash and cash equivalents	105,623	(157,870)
Cash and cash equivalents at beginning of the period	368,865	327,429
Cash and cash equivalents at end of the period	474,488	169,559
Supplemental Disclosure of Cash Flow Information:
Cash paid for income taxes	480	1,510
Cash paid for interest (net of amount capitalized)	61,414	55,910
Non-cash investing and financing activities:
Additions to property, plant and equipment in accounts payable	168,635	101,178
Right-of-use asset obtained in exchange for finance lease liability	$ 226,618	$ 0