Goodwill and Intangible Assets - Changes in Goodwill Balances by Segment (Detail)	9 Months Ended
	Sep. 30, 2015 USD ($)
Goodwill [Line Items]
Goodwill, beginning balance	$ 13,072,000
Acquisitions	4,158,000
Foreign Exchange	(21,000)
Goodwill, ending balance	17,209,000
SLPE [Member]
Goodwill [Line Items]
Goodwill, beginning balance	4,230,000
Foreign Exchange	17,000
Goodwill, ending balance	4,247,000
High Power Group [Member] | MTE Corporation [Member]
Goodwill [Line Items]
Goodwill, beginning balance	8,189,000
Goodwill, ending balance	8,189,000
SL-MTI [Member]
Goodwill [Line Items]
Goodwill, beginning balance	653,000
Acquisitions	4,158,000
Foreign Exchange	(38,000)
Goodwill, ending balance	$ 4,773,000