Segment Information - Selected Financial Details Regarding the Company's Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Revenue	$ 17,585	$ 11,725	$ 47,184	$ 39,029
Gross profit	2,867	1,689	8,243	5,634
Income (loss) from domestic operations	756	123	1,754	92
Foreign operations expenses	(66)	(23)	(204)	(246)
Net equity income from foreign joint ventures' operations	368	723	2,936	2,325
Income from domestic operations and net equity income from foreign joint ventures' operations	1,124	846	4,690	2,417
Gross profit, percentage	16.00%	14.00%	17.00%	14.00%
Income (loss) from domestic operations, Percentage	4.00%	1.00%	4.00%	0.00%
Technical Products and Services [Member]
Segment Reporting Information [Line Items]
Revenue	13,970	8,903	35,607	27,373
Gross profit	2,428	1,507	6,117	4,464
Income (loss) from domestic operations	2,188	1,389	5,372	3,941
Gross profit, percentage	17.00%	17.00%	17.00%	16.00%
Income (loss) from domestic operations, Percentage	16.00%	16.00%	15.00%	14.00%
Electrical and Instrumentation Construction [Member]
Segment Reporting Information [Line Items]
Revenue	2,266	1,495	7,136	7,102
Gross profit	331	61	1,496	593
Income (loss) from domestic operations	331	61	1,496	593
Gross profit, percentage	15.00%	4.00%	21.00%	8.00%
Income (loss) from domestic operations, Percentage	15.00%	4.00%	21.00%	8.00%
American Access Technologies [Member]
Segment Reporting Information [Line Items]
Revenue	1,349	1,327	4,441	4,554
Gross profit	108	121	630	577
Income (loss) from domestic operations	(215)	(227)	(350)	(530)
Gross profit, percentage	8.00%	9.00%	14.00%	13.00%
Income (loss) from domestic operations, Percentage	(16.00%)	(17.00%)	(8.00%)	(12.00%)
Corporate and other unallocated expenses [Member]
Segment Reporting Information [Line Items]
Income (loss) from domestic operations	(1,548)	(1,100)	(4,764)	(3,912)
Income (loss) from domestic operations, Percentage	(9.00%)	(9.00%)	(10.00%)	(10.00%)
BOMAY [Member]
Segment Reporting Information [Line Items]
Net equity income from foreign joint ventures' operations	475	624	2,123	2,385
MIEFE [Member]
Segment Reporting Information [Line Items]
Net equity income from foreign joint ventures' operations	(12)	(1)	146	19
AAG [Member]
Segment Reporting Information [Line Items]
Net equity income from foreign joint ventures' operations	(29)	123	871	167
Foreign Operations [Member]
Segment Reporting Information [Line Items]
Foreign operations expenses	$ (66)	$ (23)	$ (204)	$ (246)