Acquisitions (Details Textual) (USD $) In Thousands, unless otherwise specified	6 Months Ended				6 Months Ended		6 Months Ended				6 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2012 Senior Notes [Member]	Mar. 16, 2011 Senior Notes [Member]	Jun. 30, 2012 Servalite [Member]	Dec. 29, 2010 Servalite [Member]	Jun. 30, 2012 Tagworks [Member]	Mar. 30, 2012 Tagworks [Member]	Oct. 31, 2011 Tagworks [Member]	Mar. 16, 2011 Tagworks [Member]	Jun. 30, 2012 Ook [Member]	Dec. 01, 2011 Ook [Member]	Jun. 30, 2012 Ook [Member] Maximum [Member]	Jun. 30, 2012 Ook [Member] Minimum [Member]
Acquisitions (Textual) [Abstract]
Purchase price						$ 21,517				$ 40,000		$ 15,323
Additional consideration									12,500
Additional contingent consideration								12,500			6,000
Period for agreement							17 years
Principal amount	50,000						50,000
Fair value of the contingent consideration		$ 0
Interest rate on senior note			10.875%	10.875%
Intangible assets and goodwill are deductible for income tax purposes					15 years		15 years				15 years
Discount rate range													3.70%	1.00%