RESTRUCTURING AND IMPAIRMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Employee severance and related costs		$ 564
Lease termination and other facility costs	$ 1,220	248
Business integration expenses	900	1,570	[1]
Asset impairments		2,792
Other costs	306	403
Pre-tax restructuring, integration and impairment expense	2,426	5,577
T And D Segment [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance and related costs		564
Lease termination and other facility costs	1,220	168
Business integration expenses	900	1,570	[1]
Asset impairments		2,792
Other costs	274	403
Pre-tax restructuring, integration and impairment expense	2,394	5,497
Critical Power Segment [Member]
Restructuring Cost and Reserve [Line Items]
Lease termination and other facility costs		80
Other costs	32
Pre-tax restructuring, integration and impairment expense	$ 32	$ 80

[1] Due to the reorganization, certain operations were transferred from Critical Power to T&D Segment.