ACQUISITIONS (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
		Jul. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Acquisitions
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory			$ 2,314
Sales Revenue, Goods, Net			669,491	$ 567,646	$ 1,877,246	$ 1,710,786
Business Combination, Bargain Purchase, Gain Recognized, Amount			(51,585)	0	(51,585)	0
Special Items Charge (Gain)			(40,715)	$ 0	(32,602)	34,348
Payments to Acquire Businesses, Net of Cash Acquired					72,468	$ 71,567
Air Liquide Welding [Member]
Acquisitions
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		$ 89,710
Indefinite-Lived Intangible Assets (Excluding Goodwill)		7,099
Sales Revenue, Goods, Net			63,000		400,000
Business Combination, Bargain Purchase, Gain Recognized, Amount			(51,585)
Business Combination, Recognized Identifiable Other Assets Acquired and Other Liabilities Assumed, Net	[1]	(20,998)
Business Combination, Consideration Transferred		135,123
Special Items Charge (Gain)					$ 11,386
Payments to Acquire Businesses, Net of Cash Acquired			$ 72,468
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	[2]	98,529
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	[3]	79,619
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	[4]	11,715
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		(66,959)
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] Consists primarily of other accrued liabilities.

[2] A portion of inventories acquired were sold in the third quarter of 2017 resulting in a $2,314 increase in cost of sales for the amortization of step up in the value of acquired inventories.

[3] 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.

[4] $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).