ACQUISITIONS - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Feb. 29, 2016	Dec. 31, 2015	Jul. 07, 2015
Business Acquisition [Line Items]
Goodwill	$ 294,918		$ 256,654
Furmanite Corporation
Business Acquisition [Line Items]
Cash and cash equivalents		$ 37,734
Accounts receivable		85,814
Inventory		38,896
Current deferred tax assets		11,563
Prepaid expenses and other current assets		19,405
Plant, property and equipment		70,539
Intangible assets		70,800
Goodwill		36,720
Other non-current assets		3,709
Total assets acquired		375,180
Accounts payable		12,360
Other accrued liabilities		26,950
Income taxes payable		229
Non-current deferred tax liabilities		37,097
Defined benefit pension liability		13,509
Other long-term liabilities		2,694
Total liabilities assumed		92,839
Net assets acquired		$ 282,341
Qualspec Group
Business Acquisition [Line Items]
Cash and cash equivalents				$ 3,981
Accounts receivable				21,495
Current deferred tax assets				279
Prepaid expenses and other current assets				1,049
Plant, property and equipment				15,472
Intangible assets				78,100
Goodwill				148,482
Other non-current assets				138
Total assets acquired				268,996
Accounts payable				2,892
Other accrued liabilities				7,581
Non-current deferred tax liabilities				2,982
Total liabilities assumed				13,455
Net assets acquired				$ 255,541