Schedule of Restructuring Activities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 3,904	$ 1,372	$ 4,879	$ 53
Restructuring expenses	909	1,363
Payments for restructuring	(1,401)	(38)
Restructuring settled without cash	(483)	(6)
United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	24	47	30	53
Restructuring expenses	0	0
Payments for restructuring	0	0
Restructuring settled without cash	(6)	(6)
United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0	164	0
Restructuring expenses	(76)	0
Payments for restructuring	0	0
Restructuring settled without cash	(88)	0
United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	0	0	0	0
Restructuring expenses	0	38
Payments for restructuring	0	(38)
Restructuring settled without cash	0	0
United Kingdom Construction And Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	3,580	1,325	4,685	0
Restructuring expenses	685	1,325
Payments for restructuring	(1,401)	0
Restructuring settled without cash	(389)	0
Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	300	0	0	0
Restructuring expenses	300	0
Payments for restructuring	0	0
Restructuring settled without cash	0	0
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	685	1,400
Employee Severance [Member] | United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Employee Severance [Member] | United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Employee Severance [Member] | United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Employee Severance [Member] | United Kingdom Construction And Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	685
Employee Severance [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	224
Facility Closing [Member] | United States Electrical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Facility Closing [Member] | United States Mechanical Construction And Facilities Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	(76)
Facility Closing [Member] | United States Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Facility Closing [Member] | United Kingdom Construction And Building Services [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0
Facility Closing [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 300