Operations by Business Segment and Geographic Information Operations by Busines Segment (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015 USD ($)	Oct. 03, 2015 USD ($)	Jul. 04, 2015 USD ($)	Apr. 04, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 27, 2014 USD ($)	Jun. 28, 2014 USD ($)	Mar. 29, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments										2
Revenues										$ 821,904	$ 789,911	$ 713,848
Income (loss) from operations		$ 4,120	$ 16,177	$ 27,796	$ (3,985)	$ 7,769	$ 17,144	$ 23,815	$ (4,725)	44,108	44,003	40,789
Interest expense										3,355	2,948	2,708
Interest income										249	295	311
Other										(5,744)	(3,050)	(2,827)
Income before income taxes										35,258	38,300	35,565
Depreciation										44,677	40,970	38,231
Amortization										2,214	2,070	1,980
Capital expenditures										56,047	55,731	45,205
Segment assets, total		394,057				381,004				394,057	381,004	333,378
Utility Services
Segment Reporting Information [Line Items]
Revenues										433,117	404,519	376,520
Income (loss) from operations										24,273	21,382	16,070
Depreciation										25,466	23,225	22,261
Amortization										144	174	359
Capital expenditures										26,853	25,994	21,642
Segment assets, total		145,306				150,002				145,306	150,002	145,021
Residential Commercial Services
Segment Reporting Information [Line Items]
Revenues										386,327	386,274	334,878
Income (loss) from operations										35,271	37,232	33,566
Depreciation										15,592	14,544	13,286
Amortization										2,062	1,896	1,440
Capital expenditures										22,853	17,490	17,577
Segment assets, total		162,679				144,413				162,679	144,413	122,542
All Other
Segment Reporting Information [Line Items]
Revenues										2,460	(882)	2,450
Income (loss) from operations										(5,368)	(6,037)	(2,869)
Depreciation										0	0	0
Amortization										0	0	0
Capital expenditures										0	0	0
Segment assets, total		0				0				0	0	0
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Revenues										0	0	0
Income (loss) from operations	[1]									(10,068)	(8,574)	(5,978)
Interest expense										3,355	2,948	2,708
Interest income										249	295	311
Other										(5,744)	(3,050)	(2,827)
Depreciation	[2]									3,619	3,201	2,684
Amortization										8	0	181
Capital expenditures										6,341	12,247	5,986
Segment assets, total	[3]	$ 86,072				$ 86,589				$ 86,072	$ 86,589	$ 65,815

[1] Reconciling adjustments from segment reporting to consolidated external financial reporting include 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.