Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities
Net income	$ 110,277	$ 122,654
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	133,232	126,112
Other amortization	21,609	19,134
Provision for credit losses	1,218	(506)
Loans originated, held for sale	(14,912)	(108,695)
Proceeds from sale of loans, held for sale	14,596	114,299
Gain on sales of investment securities, net and equity-method investment	0	(8,123)
Gain on sale of loans, net	(360)	(1,449)
Deferred income taxes	(1,309)	(14,683)
Share-based compensation expense	5,919	5,593
Allowance for equity funds used during construction	(7,073)	(4,879)
Other	(3,710)	(3,858)
Changes in assets and liabilities
Decrease (increase) in accounts receivable and unbilled revenues, net	103,695	(101,641)
Decrease (increase) in fuel oil stock	47,963	(119,890)
Decrease (increase) in regulatory assets	(10,620)	12,956
Increase in regulatory liabilities	22,782	11,288
Increase in accounts, interest and dividends payable	34,946	62,115
Change in prepaid and accrued income taxes, tax credits and utility revenue taxes	(45,171)	22,173
Decrease in defined benefit pension and other postretirement benefit plans liability	(4,304)	(2,698)
Change in other assets and liabilities	(37,161)	(55,260)
Net cash provided by operating activities	371,617	74,642
Cash flows from investing activities
Available-for-sale investment securities purchased	0	(366,177)
Principal repayments on available-for-sale investment securities	68,279	209,094
Proceeds from repayments or maturities of held-to-maturity investment securities	35,604	7,932
Purchase of stock from Federal Home Loan Bank	(62,400)	(18,720)
Redemption of stock from Federal Home Loan Bank	70,960	15,520
Net increase in loans held for investment	(208,042)	(212,744)
Proceeds from sale of commercial loans	66,655	0
Purchase of loans held for investment	(26,195)	0
Capital expenditures	(235,875)	(147,749)
Other	8,160	15,813
Net cash used in investing activities	(282,854)	(497,031)
Cash flows from financing activities
Net increase (decrease) in deposit liabilities	(104,771)	81,324
Net increase (decrease) in short-term borrowings with original maturities of three months or less	(91,438)	70,019
Net increase (decrease) in other bank borrowings with original maturities of three months or less	(596,810)	153,305
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	250,000	67,312
Repayment of long-term debt	(62,426)	(15,030)
Withheld shares for employee taxes on vested share-based compensation	(2,356)	(3,079)
Common stock dividends	(78,893)	(76,602)
Preferred stock dividends of subsidiaries	(946)	(946)
Other	(1,662)	(318)
Net cash provided by (used in) financing activities	25,698	275,985
Net increase (decrease) in cash, cash equivalents and restricted cash	114,461	(146,404)
Cash, cash equivalents and restricted cash, beginning of period	204,927	311,462
Cash, cash equivalents and restricted cash, end of period	319,388	165,058
Less: Restricted cash	(5,104)	(5,386)
Cash and cash equivalents	$ 314,284	$ 159,672