SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND PRACTICES - Additional Information (Details) shares in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) shares	Jun. 30, 2017 USD ($) employee country segment Location customer	Jun. 30, 2016 USD ($) shares	Dec. 31, 2016 USD ($)	Jan. 01, 2017 USD ($)	Dec. 01, 2016 USD ($)	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment		3
Number of locations in which company operates (more than) | Location		220
Number of countries in which the company operates | country		20
Number of employees (more than) | employee		7,100
Significant Accounting Policies [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	0.3		0.4
Cash and cash equivalents	$ 65,440,000	$ 29,154,000	$ 65,440,000	$ 46,216,000			$ 44,825,000
Goodwill impairment		$ 0		0
Discounted cash flow, forecast period		5 years
Goodwill impairment test, number of market-based approaches		2
Market capitalization in excess of carrying amount		$ 175,000,000				$ 437,000,000
Market capitalization in excess of carrying amount, percentage		33.00%				80.00%
Goodwill		$ 358,576,000		355,786,000
Workers compensation our self-insured retention		1,000,000.0
Automobile liability self-insured retention		500,000
General liability claims we have an effective self-insured retention		3,000,000.0
Medical claims, our self-insured retention		350,000
Environmental liability claims, our self-insured retention		1,000,000
Unbilled revenues		$ 80,040,000		39,719,000
Sales Revenue, Net | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Number of customers accounted for more than specified percentage of consolidated revenues | customer		0
Europe and Asia
Significant Accounting Policies [Line Items]
Cash and cash equivalents		$ 9,400,000		14,000,000
ASU 2016-09
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment to opening balance of retained earnings					$ 1,000,000
Team Qualspec
Significant Accounting Policies [Line Items]
Fair value in excess of consolidated net assets, percentage		65.00%
Goodwill		$ 214,525,000		213,475,000
Team Furmanite
Significant Accounting Policies [Line Items]
Fair value in excess of consolidated net assets, percentage		46.00%
Goodwill		$ 110,097,000		$ 109,059,000