GOODWILL AND INTANGIBLE ASSETS - Impairment (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 336,754,000	$ 321,110,000
ESS
Indefinite-lived Intangible Assets [Line Items]
Goodwill	102,209,000	94,314,000
Energy & Mining
Indefinite-lived Intangible Assets [Line Items]
Goodwill	78,916,000	72,212,000
Coatings Segment
Indefinite-lived Intangible Assets [Line Items]
Goodwill	60,520,000	$ 59,569,000
Offshore Structures | Energy & Mining
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 14,645