Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net income	$ 151,866	$ 185,207
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	200,722	190,075
Other amortization	32,744	28,916
Provision for credit losses	10,053	(692)
Loans originated, held for sale	(37,288)	(120,195)
Proceeds from sale of loans, held for sale	36,086	126,357
Gain on sales of investment securities, net and equity-method investment	0	(8,123)
Gain on sale of loans, net	(701)	(1,630)
Deferred income taxes	(5,594)	(21,631)
Share-based compensation expense	8,281	7,337
Allowance for equity funds used during construction	(11,073)	(7,431)
Other	(5,315)	(5,392)
Changes in assets and liabilities
Decrease (increase) in accounts receivable and unbilled revenues, net	41,494	(159,619)
Decrease (increase) in fuel oil stock	38,587	(127,413)
Decrease in regulatory assets	13,908	34,278
Increase in regulatory liabilities	32,454	29,294
Increase in accounts, interest and dividends payable	70,850	39,009
Change in prepaid and accrued income taxes, tax credits and utility revenue taxes	(24,860)	73,279
Decrease in defined benefit pension and other postretirement benefit plans liability	(6,722)	(4,228)
Change in other assets and liabilities	(70,354)	(44,411)
Net cash provided by operating activities	475,138	212,987
Cash flows from investing activities
Available-for-sale investment securities purchased	0	(366,177)
Principal repayments on available-for-sale investment securities	117,042	285,519
Proceeds from repayments or maturities of held-to-maturity investment securities	52,823	10,433
Purchase of stock from Federal Home Loan Bank	(76,040)	(93,000)
Redemption of stock from Federal Home Loan Bank	84,600	88,000
Net increase in loans held for investment	(283,126)	(395,185)
Proceeds from sale of commercial loans	94,665	0
Purchase of loans held for investment	(26,195)	(77,274)
Capital expenditures	(342,364)	(236,278)
Contributions to low income housing investments	(418)	(740)
Acquisition of business	0	(25,706)
Other	9,375	15,646
Net cash used in investing activities	(369,638)	(794,762)
Cash flows from financing activities
Net increase (decrease) in deposit liabilities	(43,655)	86,673
Net increase (decrease) in short-term borrowings with original maturities of three months or less	(137,650)	117,127
Net increase (decrease) in other bank borrowings with original maturities of three months or less	(596,810)	320,735
Proceeds from issuance of short-term debt	65,000	0
Repayment of short-term debt	(100,000)	0
Proceeds from issuance of other bank borrowings	1,000,000	0
Repayment of other bank borrowings	(250,000)	0
Proceeds from issuance of long-term debt	625,000	67,312
Repayment of long-term debt	(64,317)	(16,752)
Withheld shares for employee taxes on vested share-based compensation	(2,356)	(3,158)
Net proceeds from issuance of common stock	437	0
Common stock dividends	(112,957)	(114,917)
Preferred stock dividends of subsidiaries	(1,417)	(1,417)
Other	(9,409)	(6,112)
Net cash provided by financing activities	371,866	449,491
Net increase (decrease) in cash, cash equivalents and restricted cash	477,366	(132,284)
Cash, cash equivalents and restricted cash, beginning of period	204,927	311,462
Cash, cash equivalents and restricted cash, end of period	682,293	179,178
Less: Restricted cash	(15,164)	(3,898)
Cash and cash equivalents	$ 667,129	$ 175,280