Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net income	$ 42,595	$ 55,194
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	68,757	66,508
Other amortization	12,093	10,362
Provision for credit losses	(2,159)	1,175
Loans originated, held for sale	(25,318)	(5,450)
Proceeds from sale of loans, held for sale	26,450	5,662
Gain on sale of loans, net	(425)	(130)
Deferred income tax expense (benefit)	1,826	(1,076)
Share-based compensation expense	1,288	2,031
Allowance for equity funds used during construction	(3,640)	(3,301)
Other	2,091	(988)
Changes in assets and liabilities
Decrease in accounts receivable and unbilled revenues, net	138,369	82,423
Decrease (increase) in fuel oil stock	(14,025)	33,429
Increase in materials and supplies	(1,329)	(4,548)
Increase in regulatory assets	(17,178)	(8,898)
Increase in regulatory liabilities	2,909	11,551
Increase in accounts, interest and dividends payable	8,462	24,748
Change in prepaid and accrued income taxes, tax credits and utility revenue taxes	(11,628)	(47,305)
Decrease in defined benefit pension and other postretirement benefit plans liability	(930)	(1,950)
Change in other assets and liabilities	(103,589)	(38,485)
Net cash provided by operating activities	124,619	180,952
Cash flows from investing activities
Principal repayments on available-for-sale investment securities	25,615	32,484
Proceeds from repayments or maturities of held-to-maturity investment securities	13,752	17,938
Purchase of stock from Federal Home Loan Bank	(21,856)	(35,960)
Redemption of stock from Federal Home Loan Bank	4,095	52,520
Net decrease (increase) in loans held for investment	42,853	(68,871)
Proceeds from sale of commercial loans	31,067	0
Purchase of loans held for investment	0	(13,012)
Capital expenditures	(99,550)	(124,297)
Contributions to low income housing investments	0	(418)
Other	(1,568)	2,148
Net cash used in investing activities	(5,592)	(137,468)
Cash flows from financing activities
Net increase (decrease) in deposit liabilities	(140,714)	60,905
Net decrease in short-term borrowings with original maturities of three months or less	0	(88,666)
Net increase (decrease) in other bank borrowings with original maturities of three months or less	73,000	(564,430)
Proceeds from issuance of short-term debt	0	65,000
Proceeds from issuance of other bank borrowings	320,000	550,000
Repayment of other bank borrowings	(550,000)	0
Proceeds from issuance of long-term debt	4,673	150,000
Repayment of long-term debt	(8,268)	(53,878)
Withheld shares for employee taxes on vested share-based compensation	(1,070)	(2,338)
Common stock dividends	0	(39,446)
Preferred stock dividends of subsidiaries	(473)	(473)
Other	(8,026)	(5,535)
Net cash provided by (used in) financing activities	(310,878)	71,139
Net increase in cash, cash equivalents and restricted cash	(191,851)	114,623
Cash, cash equivalents and restricted cash, beginning of period	694,574	204,927
Cash, cash equivalents and restricted cash, end of period	502,723	319,550
Less: Restricted cash	(17,531)	(4,216)
Cash and cash equivalents	$ 485,192	$ 315,334