Roll Forward of Goodwill from Acquisition (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill Roll Forward
Goodwill, Beginning balance	$ 69,685,000	$ 51,735,000
Goodwill arising from the acquisition of Etratech		14,881,000
Reclassification to assets held for sale	(6,844,000)
Impairment of goodwill	(6,151,000)	0	$ 0
Exchange rate impact	(1,379,000)	3,069,000
Goodwill, Ending balance	$ 55,311,000	$ 69,685,000	$ 51,735,000