ACQUISITIONS (Details) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended				6 Months Ended				12 Months Ended
		Jul. 31, 2017		Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017		Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Acquisitions
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory												$ 4,578
Business Combination Receivable From Seller														$ 10,983
Sales Revenue, Goods, Net				$ 790,052		$ 626,858		$ 1,547,748		$ 1,207,755
Business Combination, Bargain Purchase, Gain Recognized, Amount												(49,650)
Special Items Charge (Gain)				12,330	[1]	$ 4,498	[2]	25,170	[1]	8,113	[2]
Payments to Acquire Businesses, Net of Cash Acquired								$ (6,235)		$ 0
Air Liquide Welding [Member]
Acquisitions
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		$ 89,442
Indefinite-Lived Intangible Assets (Excluding Goodwill)		7,099
Sales Revenue, Goods, Net				$ 207,000									$ 400,000
Business Combination, Bargain Purchase, Gain Recognized, Amount		(49,650)
Business Combination, Recognized Identifiable Other Assets Acquired and Other Liabilities Assumed, Net	[3]	(27,210)
Business Combination, Consideration Transferred		135,123
Payments to Acquire Businesses, Net of Cash Acquired		61,953	[4]									$ 61,953
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	[5]	97,803
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	[6]	73,056
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	[7]	11,715
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		(65,640)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension Liability		$ (67,563)
Trademarks and Trade Names [Member] | Air Liquide Welding [Member]
Acquisitions
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Other Intangible Assets, Net		$ 1,183
Other Intangible Assets [Member] | Air Liquide Welding [Member]
Acquisitions
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		9 years
Other Intangible Assets, Net		$ 3,433

[1] In the three months ended June 30, 2018, special items reflect rationalization and asset impairment charges of $11,542 in International Welding and transaction and integration costs of $788 in Corporate/Eliminations related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements. In the six months ended June 30, 2018, special items reflect pension settlement charges of $758 in Americas Welding, rationalization and asset impairment charges of $21,717 in International Welding and transaction and integration costs of $2,695 in Corporate / Eliminations related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements.

[2] In the three and six months ended June 30, 2017, special items in Corporate / Eliminations reflect transaction and integration costs of $4,498 and $8,113, respectively, related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements.

[3] Consists primarily of other accrued liabilities.

[4] Reflects a receivable from seller for an agreed upon purchase price adjustment. The payment of $10,983 was received in the first quarter of 2018.

[5] Inventories acquired were sold in 2017 resulting in a $4,578 increase in Cost of goods sold for the year ended December 31, 2017 related to the amortization of step up in the value of acquired inventories.

[6] Property, plant and equipment acquired includes a number of manufacturing and distribution sites, including the related facilities, land and leased sites, and machinery and equipment for use in manufacturing operations.

[7] $7,099 of the intangible asset balance was assigned to a trade name expected to have an indefinite life. Of the remaining amount, $1,183 was assigned to a finite-lived trade name (10 year weighted average useful life) and $3,433 was assigned to other intangible assets (9 year weighted average life).