Consolidated Statements Of Cash Flow - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 315,106	$ 182,142
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	221,623	186,078
Deferred income taxes	12,645	1,120
Provision for doubtful accounts	21,220	23,598
Stock-based compensation	7,343	5,842
Gain on sale of utility systems and other assets	(1,208)	(339)
Net change in receivables, inventory and prepayments	(20,488)	24,886
Net change in payables, accrued interest, accrued taxes and other accrued liabilities	16,181	12,431
Pension and other postretirement benefits contributions	(15,109)	(16,100)
Other	4,539	997
Net cash flows from operating activities	561,852	420,655
Cash flows from investing activities:
Property, plant and equipment additions, including the debt component of allowance for funds used during construction of $2,885 and $2,957	(675,845)	(554,141)
Acquisitions of utility systems, net	(36,325)	(3,467,032)
Net proceeds from the sale of other assets	1,420	1,063
Other	(120)	465
Net cash flows used in investing activities	(710,870)	(4,019,645)
Cash flows from financing activities:
Customers' advances and contributions in aid of construction	12,473	7,475
Repayments of customers' advances	(3,091)	(3,992)
Net repayments of short-term debt	(31,616)	(160,420)
Proceeds from long-term debt	795,153	2,957,663
Repayments of long-term debt	(717,816)	(1,647,354)
Change in cash overdraft position	(23,255)	18,166
Proceeds from issuance of common stock under dividend reinvestment plan	12,597	12,322
Proceeds from issuance of common stock from private placement		729,301
Proceeds from issuance of common stock from forward equity sale agreement	299,739
Proceeds from exercised stock options	3,293	1,215
Repurchase of common stock	(3,287)	(4,345)
Dividends paid on common stock	(190,862)	(171,079)
Other	599	(390)
Net cash flows from financing activities	153,927	1,738,562
Net change in cash and cash equivalents	4,909	(1,860,428)
Cash and cash equivalents at beginning of period	4,827	1,868,922
Cash and cash equivalents at end of period	9,736	8,494
Non-cash investing activities:
Property, plant and equipment additions purchased at the period end, but not yet paid for	78,727	96,982
Non-cash customer advances and contributions in aid of construction	$ 30,075	$ 28,321