SEGMENT INFORMATION (Details) $ / shares in Units, $ in Thousands	3 Months Ended								9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares		Jun. 30, 2020 $ / shares	Mar. 31, 2020 $ / shares	Sep. 30, 2019 USD ($) $ / shares		Jun. 30, 2019 $ / shares	Mar. 31, 2019 $ / shares	Sep. 30, 2020 USD ($) segment $ / shares		Sep. 30, 2019 USD ($) $ / shares
Financial information for the reportable segments
Rationalization and asset impairment charges (Note 6)	$ 6,257				$ 1,495				$ 36,016		$ 6,337
Number of operating segments | segment									3
Net sales	668,888				730,783				$ 1,961,606		2,266,965
Inter-segment sales	0				0				0		0
Total	668,888				730,783				1,961,606		2,266,965
EBIT, as adjusted	88,300				93,700				243,143		305,814
Special items charge (gain)	9,445	[1]			(4,497)	[2]			43,344	[1]	(6)	[2]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net									0		7,601
EBIT	78,855				98,197				199,799		305,820
Interest income	293				491				1,576		2,047
Interest expense	(5,845)				(6,891)				(18,467)		(19,668)
Income before income taxes	$ 73,303				$ 91,797				$ 182,908		$ 288,199
Cash dividends declared per share | $ / shares	$ 0.49		$ 0.49	$ 0.49	$ 0.47		$ 0.47	$ 0.47	$ 1.47		$ 1.41
The Harris Products Group
Financial information for the reportable segments
Net sales	$ 100,416				$ 81,884				$ 266,280		$ 253,348
Inter-segment sales	1,898				1,857				5,376		5,837
Total	102,314				83,741				271,656		259,185
EBIT, as adjusted	17,587				11,038				41,792		35,045
Special items charge (gain)	0	[1]			0	[2]			0	[1]	0	[2]
EBIT	17,587				11,038				41,792		35,045
Corporate / Eliminations
Financial information for the reportable segments
Acquisition Transaction and Integration Costs											1,804
Net sales	0				0				0		0
Inter-segment sales	(36,164)				(37,399)				(100,687)		(113,975)
Total	(36,164)				(37,399)				(100,687)		(113,975)
EBIT, as adjusted	(1,839)				(1,632)				(4,902)		(8,643)
Special items charge (gain)	0	[1]			0	[2]			0	[1]	1,804	[2]
EBIT	(1,839)				(1,632)				(4,902)		(10,447)
Americas Welding
Financial information for the reportable segments
Rationalization and asset impairment charges (Note 6)	3,856								27,719		1,716
Net sales	371,535				443,521				1,123,299		1,377,847
Inter-segment sales	29,368				31,101				81,644		95,300
Total	400,903				474,622				1,204,943		1,473,147
EBIT, as adjusted	59,120				74,110				176,524		240,713
Special items charge (gain)	7,044	[1]			0	[2]			34,241	[1]	3,115	[2]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Gain (Loss) Due to Settlement and Curtailment	(3,188)								(6,522)
Business Combination, Inventory Step Up											1,399
EBIT	52,076				74,110				142,283		237,598
International Welding
Financial information for the reportable segments
Rationalization and asset impairment charges (Note 6)	2,401				1,495				8,297		4,621
Net sales	196,937				205,378				572,027		635,770
Inter-segment sales	4,898				4,441				13,667		12,838
Total	201,835				209,819				585,694		648,608
EBIT, as adjusted	13,432				10,184				29,729		38,699
Special items charge (gain)	2,401	[1]			(4,497)	[2]			9,103	[1]	(4,925)	[2]
Business Combination, Inventory Step Up					1,609				806		1,609
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net					7,601						7,601
Gain (Loss) on Disposition of Assets											3,554
EBIT	$ 11,031				$ 14,681				$ 20,626		$ 43,624

[1] In the three months ended September 30, 2020, special items reflect Rationalization and asset impairment charges of $3,856 and $2,401 in Americas Welding and International Welding, respectively, and pension settlement charges of $3,188 in Americas Welding. In the nine months ended September 30, 2020, special items reflect Rationalization and asset impairment charges of $27,719 and $8,297 in Americas Welding and International Welding, respectively, amortization of step up in value of acquired inventories of $806 related to an acquisition in International Welding and pension settlement charges of $6,522 in Americas Welding.

[2] In the three months ended September 30, 2019, special items reflect Rationalization and asset impairment charges $1,495, amortization of step up in value of acquired inventories of $1,609 related to the acquisition of Askaynak and a gain on change in control of $7,601 related to the acquisition of Askaynak in International Welding. In the nine months ended September 30, 2019, special items reflect Rationalization and asset impairment charges of $1,716 and $4,621 in Americas Welding and International Welding, respectively, amortization of step up in value of acquired inventories of $1,399 in Americas Welding and $1,609 related to the acquisition of Askaynak in International Welding, gains on disposals of assets of $3,554 in International Welding and acquisition transaction and integration costs of $1,804 in Corporate / Eliminations related to the Air Liquide Welding acquisition and a gain on change in control of $7,601 related to the acquisition of Askaynak in International Welding.