SEGMENT INFORMATION (Financial Information of Reportable Segments) (Details) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Financial information for the reportable segments
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment										$ (1,696)		$ (4,232)				$ (758)
Net Sales		$ 736,307		$ 730,783		$ 777,008		$ 759,174		743,827		737,099		$ 790,052		757,696		$ 3,003,272		$ 3,028,674	$ 2,624,431
Revenue from Related Parties																		0		0	0
Segment, including Inter-segment, sales																		3,003,272		3,028,674	2,624,431
EBIT, as adjusted																		400,753		422,694	370,338
Special items charge (Gain)																		8,845		36,469	(15,330)
EBIT																		391,908		386,225	385,668
Interest income																		2,527		6,938	4,788
Interest expense																		(25,942)		(24,503)	(24,220)
Income before income taxes		80,294	[1]	91,797	[2]	103,484	[3]	92,918	[4]	94,455	[1]	95,744	[2]	94,263	[3]	84,198	[4]	368,493		368,660	366,236
Total assets		2,371,213								2,349,825								2,371,213		2,349,825	2,406,547
Equity investments in affiliates		4,274								31,228								4,274		31,228	28,526
Capital expenditures																		69,615		71,246	61,656
Depreciation and amortization																		81,487		72,346	68,115
Rationalization and asset impairment charges (gains)		8,851		1,495		1,307		3,535		932		2,636		11,542		10,175		15,188		25,285	6,590
Business Combination, Inventory Step Up				1,609		1,399															4,578
Acquisition Transaction and Integration Costs						1,014		$ 790		833		$ 970		$ 788		$ 1,907		1,804		4,498	15,002
Business Combination, Bargain Purchase, Gain Recognized, Amount																		0		0	49,650
Gain (Loss) on Disposition of Assets						$ 3,554
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net																		7,601		0	0
The Harris Products Group
Financial information for the reportable segments
Net Sales																		333,150		302,389	290,628
Revenue from Related Parties																		7,487		6,969	8,190
Segment, including Inter-segment, sales																		340,637		309,358	298,818
EBIT, as adjusted																		45,701		36,564	36,442
Special items charge (Gain)																		1,770	[5]	0	0
EBIT																		43,931		36,564	36,442
Total assets		203,602								203,095								203,602		203,095	175,151
Equity investments in affiliates		0								0								0		0	0
Capital expenditures																		7,383		2,909	3,949
Depreciation and amortization																		4,636		3,045	2,885
Rationalization and asset impairment charges (gains)																		1,770
Corporate / Eliminations
Financial information for the reportable segments
Net Sales																		0		0	0
Revenue from Related Parties																		(148,520)		(144,481)	(124,432)
Segment, including Inter-segment, sales																		(148,520)		(144,481)	(124,432)
EBIT, as adjusted																		(10,948)		(8,887)	309
Special items charge (Gain)	[6]																	1,804		4,498	(34,648)
EBIT																		(12,752)		(13,385)	34,957
Total assets		(154,543)								(99,307)								(154,543)		(99,307)	57,990
Equity investments in affiliates		0								0								0		0	0
Capital expenditures																		0		0	0
Depreciation and amortization																		(462)		(91)	(172)
Acquisition Transaction and Integration Costs																		1,804		4,498	15,002
Americas Welding [Member]
Financial information for the reportable segments
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment																				(6,686)	(8,150)
Goodwill, Impairment Loss																					1,091
Net Sales																		1,815,746		1,806,514	1,609,779
Revenue from Related Parties																		123,342		118,936	97,382
Segment, including Inter-segment, sales																		1,939,088		1,925,450	1,707,161
EBIT, as adjusted																		315,719		340,744	291,866
Special items charge (Gain)	[7]																	3,115		6,686	9,242
EBIT																		312,604		334,058	282,624
Total assets		1,490,395								1,418,905								1,490,395		1,418,905	1,253,411
Equity investments in affiliates		4,274								4,204								4,274		4,204	4,037
Capital expenditures																		39,106		42,053	43,158
Depreciation and amortization																		55,300		47,008	47,038
Rationalization and asset impairment charges (gains)																		1,716
Business Combination, Inventory Step Up																		1,399
International Welding [Member]
Financial information for the reportable segments
Net Sales																		854,376		919,771	724,024
Revenue from Related Parties																		17,691		18,576	18,860
Segment, including Inter-segment, sales																		872,067		938,347	742,884
EBIT, as adjusted																		50,281		54,273	41,721
Special items charge (Gain)	[8]																	2,156		25,285	10,076
EBIT																		48,125		28,988	31,645
Total assets		831,759								827,132								831,759		827,132	919,995
Equity investments in affiliates		$ 0								$ 27,024								0		27,024	24,489
Capital expenditures																		23,126		26,284	14,549
Depreciation and amortization																		22,013		22,384	18,364
Rationalization and asset impairment charges (gains)																		11,702		$ 25,285	5,498
Business Combination, Inventory Step Up																		1,609			$ 4,578
Gain (Loss) on Disposition of Assets																		3,554
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net				$ 7,601														$ 7,601

[1] 2019 includes special item charges of $8,851 ($7,284 after-tax) for Rationalization and asset impairment charges. 2018 includes special item charges of $1,696 ($1,272 after-tax) for pension settlement charges, $932 ($841 gain after-tax) for Rationalization and asset impairment charges and gains or losses on the disposal of assets, a $4,424 credit related to the U.S. Tax Act and acquisition-related items including $833 ($690 after-tax) for acquisition transaction and integration costs.

[2] 2019 includes special item charges of $1,495 ($1,240 after-tax) for Rationalization and asset impairment charges, $1,609 for amortization of step up in value of acquired inventories and $7,601 for a gain on change in control related to the acquisition of Askaynak. 2018 includes special item charges of $4,232 ($3,176 after-tax) for pension settlement charges, $2,636 ($2,575 after-tax) for Rationalization and asset impairment charges, an adjustment to taxes on unremitted foreign earnings related to the U.S. Tax Act of $2,323 and acquisition-related items including $970 ($797 after-tax) for acquisition transaction and integration costs.

[3] 2019 includes special item charges of $3,554 ($2,586 after-tax) for gains on the disposal of assets, $1,399 ($1,049 after-tax) for amortization of step up in value of acquired inventories, $1,014 ($867 after-tax) for acquisition transaction and integration costs, $1,307 ($937 after-tax) for Rationalization and asset impairment charges and $4,852 for the settlement of a tax item as well as tax deductions associated with an investment in a subsidiary. 2018 includes special item charges of $11,542 ($10,362 after-tax) for Rationalization and asset impairment charges and $788 ($675 after-tax) for acquisition transaction and integration costs.

[4] 2019 includes special item charges of $3,535 ($2,814 after-tax) for Rationalization and asset impairment charges and $790 ($698 after-tax) for acquisition transaction and integration costs. 2018 includes special item charges of $758 ($569 after-tax) for pension settlement charges, $10,175 ($7,870 after-tax) for Rationalization and asset impairment charges, an adjustment to taxes on unremitted foreign earnings related to the U.S. Tax Act of $2,500 and $1,907 ($1,520 after-tax) for acquisition transaction and integration costs.

[5] Rationalization and asset impairment charges of $1,770

[6] acquisition transaction and integration costs of $1,804 related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements. 2018 special items reflect acquisition transaction and integration costs of $4,498 related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements. 2017 special items reflect a bargain purchase gain of $49,650 and acquisition transaction and integration costs of $15,002 related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements.

[7] 2019 special items reflect Rationalization and asset impairment charges of $1,716 and amortization of step up in value of acquired inventories of $1,399 related to the acquisition of Baker. 2018 special items reflect pension settlement charges of $6,686 in Americas Welding related to lump sum pension payments. 2017 special items reflect pension settlement charges of $8,150 related to lump sum pension payments, as well as non-cash charges of $1,091 related to the impairment of goodwill.

[8] Rationalization and asset impairment charges of $11,702, amortization of step up in value of acquired inventories of $1,609 related to the acquisition of Askaynak, gains on disposals of assets of $3,554 and a gain on change in control of $7,601 related to the acquisition of Askaynak. 2018 special items reflect Rationalization and asset impairment charges of $25,285 related to employee severance, asset impairments, gains or losses on disposal of assets and other related costs. 2017 special items reflect amortization of step up in value of acquired inventories of $4,578 related to the Air Liquide Welding acquisition as discussed in Note 4 to the consolidated financial statements, as well as Rationalization and asset impairment charges of $5,498 related to employee severance, asset impairments and other related costs.