Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016
Goodwill [Line Items]
Balance beginning of period	$ 2,350,996		$ 2,598,136
Goodwill attributable to acquisitions	181,204	[1]	16,559
Goodwill impairment	(150,200)
Impact of foreign currency translation and other	156,544		(263,699)
Balance end of period	2,538,544		2,350,996
Accumulated goodwill impairment as of December 31, 2017	(150,200)
Air and Gas [Member]
Goodwill [Line Items]
Balance beginning of period	1,053,543		1,206,715
Goodwill attributable to acquisitions	107,024	[1]	1,317
Goodwill impairment	(150,200)
Impact of foreign currency translation and other	97,805		(154,489)
Balance end of period	1,108,172		1,053,543
Accumulated goodwill impairment as of December 31, 2017	(150,200)
Fabrication Technology [Member]
Goodwill [Line Items]
Balance beginning of period	1,297,453		1,391,421
Goodwill attributable to acquisitions	74,180	[1]	15,242
Goodwill impairment	0
Impact of foreign currency translation and other	58,739		(109,210)
Balance end of period	1,430,372		$ 1,297,453
Accumulated goodwill impairment as of December 31, 2017	$ 0

[1] Includes purchase accounting adjustments associated with the two air and gas handling acquisitions and three fabrication technology acquisitions completed during the year ended December 31, 2017. See Note 5, “Acquisitions” for further discussion.