Schedule of Restructuring Activities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 541	$ 155	$ 541	$ 155	$ 281	$ 194
Restructuring expenses	433	176	441	401
Payments for restructuring			(181)	(440)
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	500	200	547	200
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses				200
Reversal of restructuring expenses	(100)		(106)
Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0	0	0	0	0
Restructuring expenses			0	300
Payments for restructuring			0	(300)
Corporate, Non-Segment [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			0
Corporate, Non-Segment [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			0
UNITED STATES | Operating Segments [Member] | United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	155	0	155	255	30
Restructuring expenses				182
Reversal of restructuring expenses			(106)
Payments for restructuring			(149)	(57)
UNITED STATES | Operating Segments [Member] | United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0	0	0	26	164
Restructuring expenses			6
Reversal of restructuring expenses				(81)
Payments for restructuring			(32)	(83)
UNITED STATES | Operating Segments [Member] | United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 541	$ 0	541	0	$ 0	$ 0
Restructuring expenses			541	0
Payments for restructuring			0	$ 0
UNITED STATES | Operating Segments [Member] | Employee Severance [Member] | United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			0
UNITED STATES | Operating Segments [Member] | Employee Severance [Member] | United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			6
UNITED STATES | Operating Segments [Member] | Employee Severance [Member] | United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			541
UNITED STATES | Operating Segments [Member] | Facility Closing [Member] | United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Reversal of restructuring expenses			(106)
UNITED STATES | Operating Segments [Member] | Facility Closing [Member] | United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			0
UNITED STATES | Operating Segments [Member] | Facility Closing [Member] | United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			$ 0