Operations by Business Segment (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 29, 2024 USD ($)	Jul. 01, 2023 USD ($)	Jun. 29, 2024 USD ($)	Jul. 01, 2023 USD ($)	Dec. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments				2
Revenues		$ 481,654	$ 445,206	$ 886,463	$ 816,540
Income (loss) from operations		46,478	49,451	46,712	60,958
Interest expense		(5,222)	(4,966)	(9,289)	(8,837)
Interest income		998	428	1,524	827
Other income (expense), net		(2,169)	(824)	(3,533)	(1,475)
Income before income taxes		40,085	44,089	35,414	51,473
Segment assets, total		1,336,458	1,038,560	1,336,458	1,038,560	$ 1,281,060
Utility
Segment Reporting Information [Line Items]
Revenues		253,860	228,324	495,196	452,900
Income (loss) from operations		21,169	17,507	34,479	33,541
Segment assets, total		375,697	379,737	375,697	379,737
Residential and commercial
Segment Reporting Information [Line Items]
Revenues		226,516	215,981	389,366	362,189
Income (loss) from operations		36,758	37,171	34,153	36,914
Segment assets, total		413,460	356,964	413,460	356,964
All other
Segment Reporting Information [Line Items]
Revenues		1,278	901	1,901	1,451
Income (loss) from operations		(6,792)	(3,227)	(14,323)	(7,251)
Segment assets, total		0	0	0	0
Reconciling Adjustments
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Income (loss) from operations	[1]	(4,657)	(2,000)	(7,597)	(2,246)
Interest expense		(5,222)	(4,966)	(9,289)	(8,837)
Interest income		998	428	1,524	827
Other income (expense), net		(2,169)	(824)	(3,533)	(1,475)
Segment assets, total	[2]	$ 547,301	$ 301,859	$ 547,301	$ 301,859

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

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