Goodwill and Intangible Assets - Changes in Goodwill Balances by Segment (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($)
Goodwill [Line Items]
Goodwill, beginning balance	$ 13,072,000
Acquisitions	6,018,000
Foreign Exchange	(86,000)
Goodwill, ending balance	19,004,000
SLPE [Member]
Goodwill [Line Items]
Goodwill, beginning balance	4,230,000
Foreign Exchange	24,000
Goodwill, ending balance	4,254,000
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	6,018,000
Foreign Exchange	(110,000)
Goodwill, ending balance	$ 6,561,000