Acquisitions (Allocation of Purchase Consideration to the Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Feb. 13, 2020	Jan. 15, 2020	Dec. 31, 2019	Aug. 30, 2019
Business Acquisition [Line Items]
Goodwill	$ 378,740			$ 329,705
Delta Separations
Business Acquisition [Line Items]
Working capital		$ 4,063
Property, plant and equipment		219
Acquired intangible assets		13,000
Other assets		951
Other liabilities		(4,027)
Goodwill		32,906
Fair value of purchase consideration		$ 47,112
Thermo Energy Systems
Business Acquisition [Line Items]
Cash			$ 135
Working capital			(19,718)
Property, plant and equipment			1,069
Acquired intangible assets			9,750
Other current assets			35
Other assets			1,335
Other liabilities			(1,335)
Goodwill			16,062
Fair value of purchase consideration			$ 7,333
Apeks
Business Acquisition [Line Items]
Cash					$ 4,154
Working capital					(1,515)
Property, plant and equipment					1,059
Acquired intangible assets					3,000
Other assets					508
Other liabilities					(1,081)
Goodwill					6,436
Fair value of purchase consideration					$ 12,561