CHANGES IN BUSINESS - Discontinued Operation and Disposition (Details) - USD ($) $ in Thousands				1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 21, 2018	Oct. 31, 2017	Oct. 11, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Income (loss) before income taxes
Income (loss) before income taxes						$ (234)	$ (15,002)
Income tax expense (benefit)						(1,398)	(3,357)
Income (loss) from discontinued operations						1,164	(11,645)
Repayments of Long-term Debt						525	31,241
Discontinued operations, disposed of by means other than sale | Electrical Solutions
Assets:
Goodwill and other intangible assets				$ 0	$ 0
Income (loss) before income taxes
Revenue							22,259
Cost of revenue							24,613
Write-down of assets held for sale					9,709
Loss (gain) on disposal of discontinued operations							9,623
Discontinued operations, disposed of by means other than sale | Koontz Wagner
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							9,300
Discontinued operations disposed of by sale | Mechanical Solutions
Assets:
Other current assets						200
Liabilities:
Other current liabilities						$ 800
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations				(6,300)			222
Proceeds from sale of business			$ 43,000
Net proceeds			40,900
Discontinued operations disposed of by sale | Mechanical Solutions | General and administrative expenses
Income (loss) before income taxes
Transition services period						9 months
Transition services expense							300
Uncollected receivables								$ 200
Discontinued operations disposed of by sale | Mechanical Solutions | Other (income) expense, (net)
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations						$ (400)
Discontinued operations disposed of by sale | Mechanical Solutions | Mexico
Income (loss) before income taxes
Proceeds from sale of property, plant and equipment		$ 3,600
Discontinued operations disposed of by sale | Mechanical Solutions | NETHERLANDS
Income (loss) before income taxes
Carrying value of property, plant and equipment				500	500
Impairment charge					200
Fair value of property, plant and equipment				$ 300	$ 300
Proceeds from sale of property, plant and equipment	$ 300
Discontinued operations disposed of by sale | Mechanical Solutions | Initial Centre Lane Term Facility
Income (loss) before income taxes
Repayments of Long-term Debt			$ 34,000
Discontinued operations disposed of by sale | Mechanical Solutions | Initial Centre Lane Term Facility | Mexico
Income (loss) before income taxes
Repayments of Long-term Debt		$ 1,900
Discontinued operations, held-for-sale or disposed of by sale
Liabilities:
Accrued compensation and benefits							259
Other current liabilities						340	381
Current liabilities of discontinued operations						340	640
Liability for pension obligation						2,708	2,781
Liability for uncertain tax positions						1,778	2,407
Long-term liabilities of discontinued operations						4,486	5,188
Total liabilities of discontinued operations						4,826	5,828
Income (loss) before income taxes
Revenue							22,259
Cost of revenue							24,613
Selling and marketing expenses							207
General and administrative expenses						21	2,634
Other						213	(38)
Income (loss) from discontinued operations before income taxes						(234)	(5,157)
Income (loss) before income taxes						(234)	(15,002)
Income tax expense (benefit)						(1,398)	(3,357)
Income (loss) from discontinued operations						1,164	(11,645)
Exit Costs | Discontinued operations, disposed of by means other than sale | Electrical Solutions
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							11,400
Bank Charges | Discontinued operations, disposed of by means other than sale | Electrical Solutions
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							4,000
Pension | Discontinued operations, disposed of by means other than sale | Electrical Solutions
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							2,900
Expected Periodic Payment						$ 300
Expected Payment Period						20 years
Lease Termination | Discontinued operations, disposed of by means other than sale | Electrical Solutions
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							1,800
Employee Salary Continuation | Discontinued operations, disposed of by means other than sale | Electrical Solutions
Income (loss) before income taxes
Loss (gain) on disposal of discontinued operations							$ 2,700