SIGNIFICANT ACQUISITIONS AND DIVESTITURES - Narrative (Details) € in Thousands, $ in Thousands			3 Months Ended		6 Months Ended
	May 27, 2019 EUR (€) Country	May 27, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	May 27, 2019 USD ($) Country	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Cash paid for acquisition, net of cash acquired					$ 94,690	$ 0
Goodwill			$ 506,852		506,852			$ 447,995
Chemogas
Business Acquisition [Line Items]
Number of countries in which entity operates (more than) | Country	70						70
Chemogas
Business Acquisition [Line Items]
Percentage of outstanding common shares acquired	100.00%						100.00%
Total amount paid on acquisition date	€ 99,503	$ 111,324
Payments to former shareholders	88,579	99,102
Payments for debt acquired in acquisition	10,924	12,222
Cash acquired	3,943						$ 4,412
Cash paid for acquisition, net of cash acquired	€ 84,636	$ 94,690
Goodwill							59,296
Transaction and integration costs			556		862
Transaction, integration and acquisition costs			$ 612	$ 893	$ 1,097	$ 1,582
Specialty Products | Chemogas
Business Acquisition [Line Items]
Goodwill							$ 59,296
Customer relationships | Chemogas
Business Acquisition [Line Items]
Amortization period	20 years	20 years
Trade name | Chemogas
Business Acquisition [Line Items]
Amortization period	2 years	2 years
Developed technology | Chemogas
Business Acquisition [Line Items]
Amortization period	10 years	10 years