Operations by Business Segment and Geographic Information Operations by Busines Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Number of Reportable Segments									2
Revenues									$ 680,153	$ 646,034	$ 591,732
Income (loss) from operations	13,337	14,652	17,270	508	11,112	13,342	16,567	(8,220)	45,767	32,801	29,612
Interest expense									(2,698)	(3,794)	(2,803)
Interest income									200	43	46
Litigation settlement					(2,900)				0	(2,900)	0
Other									(2,611)	(2,850)	(2,521)
Income before income taxes									40,658	23,300	24,334
Depreciation									37,365	37,818	35,530
Amortization									1,742	1,908	1,791
Capital expenditures									29,734	34,701	34,753
Segment assets, total	330,932				303,734				330,932	303,734	288,307
Utility Services [Member]
Segment Reporting Information [Line Items]
Revenues									327,917	323,061	299,474
Income (loss) from operations									16,211	10,790	14,851
Depreciation									21,242	22,308	20,977
Amortization									494	484	467
Capital expenditures									15,071	16,304	20,808
Segment assets, total	134,589				126,481				134,589	126,481	118,016
Residential Commercial Services [Member]
Segment Reporting Information [Line Items]
Revenues									288,167	266,402	253,547
Income (loss) from operations									28,359	21,593	17,776
Depreciation									11,974	11,917	12,106
Amortization									1,004	994	485
Capital expenditures									9,981	12,961	9,663
Segment assets, total	115,567				100,749				115,567	100,749	89,580
All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues									64,069	56,571	38,711
Income (loss) from operations									4,958	6,743	1,895
Depreciation									1,864	1,666	1,267
Amortization									25	27	9
Capital expenditures									951	1,338	761
Segment assets, total	22,436				16,011				22,436	16,011	13,026
Significant Reconciling Items [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Income (loss) from operations									(3,761)	(6,325)	(4,910)
Interest expense									(2,698)	(3,794)	(2,803)
Interest income									200	43	46
Litigation settlement										(2,900)
Other									(2,611)	(2,850)	(2,521)
Depreciation									2,285	1,927	1,180
Amortization									219	403	830
Capital expenditures									3,731	4,098	3,521
Segment assets, total	$ 58,340				$ 60,493				$ 58,340	$ 60,493	$ 67,685