Operations by Business Segment and Geographic Information Operations by Busines Segment (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2023 USD ($)		Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments		2
Revenues		$ 1,693,481		$ 1,511,081	$ 1,378,053
Income (loss) from operations		114,207		100,236	101,266
Interest expense		13,745		6,129	4,973
Interest income		1,894		955	175
Other income (expense), net		(5,120)		(9,863)	(7,021)
Income before income taxes		97,236		85,199	89,447
Depreciation		53,571		51,969	52,927
Amortization		5,072		3,228	3,044
Capital expenditures		87,322		88,738	75,691
Segment assets, total		1,281,060		956,221	772,941
Utility Services
Segment Reporting Information [Line Items]
Revenues		934,977		840,553	765,072
Income (loss) from operations		63,414		62,267	73,893
Depreciation		21,565		22,791	25,364
Amortization		1,873		776	611
Capital expenditures		21,716		26,178	23,303
Segment assets, total		399,059		362,399	298,070
Residential Commercial Services
Segment Reporting Information [Line Items]
Revenues		754,455		666,972	610,666
Income (loss) from operations		71,822		58,310	60,261
Depreciation		29,843		26,294	24,634
Amortization		3,199		2,452	2,430
Capital expenditures		43,147		44,173	36,506
Segment assets, total		367,745		313,401	275,204
All Other
Segment Reporting Information [Line Items]
Revenues		4,049		3,556	2,315
Income (loss) from operations		(12,211)		(14,993)	(27,016)
Depreciation		0		0	0
Amortization		0		0	0
Capital expenditures		0		0	0
Segment assets, total		0		0	0
Reconciling  Adjustments
Segment Reporting Information [Line Items]
Revenues		0		0	0
Income (loss) from operations		(8,818)	[1]	(5,348)	(5,872)	[1]
Interest expense		13,745		6,129	4,973
Interest income		1,894		955	175
Other income (expense), net		(5,120)		(9,863)	(7,021)
Depreciation	[2]	2,163		2,884	2,929
Amortization		0		0	3
Capital expenditures		22,459		18,387	15,882
Segment assets, total		$ 514,256	[3]	$ 280,421	$ 199,667	[3]

[1] Reclassification of depreciation expense and allocation of corporate expenses.

[2] Adjustments to declining-balance method depreciation expense from straight-line method and depreciation and amortization of corporate assets.

[3] Corporate assets include cash, prepaid expenses, corporate facilities, enterprise-wide information systems and other nonoperating assets.