Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net income	$ 96,831	$ 63,116	$ 65,584
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	100,935	91,288	85,707
Amortization of debt premium and expenses	412	744	1,099
Changes in normalized deferred income taxes	34,440	15,346	20,909
Change in value of life insurance contracts	(4,293)	(5,104)	2,334
Allowance for equity funds used during construction	(4,976)	(6,685)	(3,954)
Stock-based compensation	4,590	6,731	3,141
Gain on sale of non-utility properties	0	(28)	(50)
Write-off of capital costs	0	698	410
Changes in operating assets and liabilities:
Receivables	(18,343)	(4,580)	20,422
Unbilled revenue	1,148	(1,452)	(3,671)
Taxes, prepaid expenses, and other assets	(3,647)	(3,545)	(587)
Accounts payable	373	10,719	4,701
Other current liabilities	(6,097)	1,282	(4,382)
Other changes in noncurrent assets and liabilities	(83,449)	264	(12,644)
Net cash provided by operating activities	117,924	168,794	179,019
Investing activities:
Utility plant expenditures	(298,651)	(273,770)	(271,707)
Proceeds from sale of non-utility assets	0	28	59
Business Acquisition, net of cash acquired	(40,483)	0	0
Payment for investments	(4,600)	0	0
Life insurance benefits	0	0	3,491
Purchase of life insurance	(2,335)	(2,216)	(4,925)
Net cash used in investing activities	(346,069)	(275,958)	(273,082)
Financing activities:
Short-term borrowings	335,000	260,000	151,000
Repayment of short-term borrowings	(140,100)	(150,000)	(361,000)
Issuance of long-term debt, net of debt issuance costs of $0 for 2020, $1,796 for 2019, and $617 for 2018	0	398,204	299,383
Advances and contributions in aid of construction	27,292	27,774	18,612
Refunds of advances for construction	(10,203)	(7,566)	(7,297)
Retirement of long-term debt	(22,141)	(405,568)	(16,532)
Repurchase of common stock	(1,679)	(2,497)	(1,645)
Issuance of common stock	83,575	20,423	0
Dividends paid	(41,768)	(38,023)	(36,043)
Net cash provided by financing activities	229,976	102,747	46,478
Change in cash, cash equivalents, and restricted cash	1,831	(4,417)	(47,585)
Cash, cash equivalents, and restricted cash at beginning of year	43,298	47,715	95,300
Cash, cash equivalents, and restricted cash at end of year	45,129	43,298	47,715
Cash paid during the year for:
Interest (net of amounts capitalized)	40,792	40,980	35,941
Income taxes	4,700	0	0
Supplemental disclosure of investing and financing non-cash activities:
Accrued payables for investments in utility plant	54,987	40,794	38,807
Utility plant contributed by developers	28,672	16,288	20,609
Litigation proceeds for TCP and MTBE contamination reclassified from liability to depreciable plant and equipment	$ 445	$ 13,968	$ 32,315