ACQUISITIONS - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Feb. 29, 2016
Business Acquisition [Line Items]
Goodwill	$ 356,347	$ 355,786
Furmanite Corporation
Business Acquisition [Line Items]
Cash and cash equivalents			$ 37,734
Accounts receivable			65,925
Inventory			25,847
Current deferred tax assets			19,857
Prepaid expenses and other current assets			23,044
Current assets of discontinued operations			18,623
Plant, property and equipment			63,259
Intangible assets			88,958
Goodwill			89,646
Non-current deferred tax assets			2,542
Other non-current assets			687
Total assets acquired			436,122
Accounts payable			12,359
Other accrued liabilities			33,127
Income taxes payable			229
Current liabilities of discontinued operations			1,434
Non-current deferred tax liabilities			91,431
Defined benefit pension liability			13,509
Other long-term liabilities			1,692
Total liabilities assumed			153,781
Net assets acquired			$ 282,341