Acquisitions (Allocation of Purchase Consideration to the Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Feb. 13, 2020	Jan. 15, 2020	Dec. 31, 2019	Aug. 30, 2019
Business Acquisition [Line Items]
Goodwill	$ 382,045			$ 329,705
Delta Separations
Business Acquisition [Line Items]
Working capital		$ 3,183
Property, plant and equipment		337
Acquired intangible assets		7,600
Other assets		923
Other liabilities		(4,189)
Goodwill		39,335
Fair value of purchase consideration		$ 47,189
Thermo Energy Systems
Business Acquisition [Line Items]
Cash			$ 58
Working capital			(16,464)
Property, plant and equipment			1,029
Acquired intangible assets			9,386
Other assets			1,285
Other liabilities			(1,285)
Goodwill			13,324
Fair value of purchase consideration			$ 7,333
Apeks
Business Acquisition [Line Items]
Cash					$ 4,154
Working capital					(1,412)
Property, plant and equipment					1,059
Acquired intangible assets					3,400
Other assets					508
Other liabilities					(1,081)
Goodwill					5,933
Fair value of purchase consideration					$ 12,561