Business Segment Information - Property and Equipment Additions, Depreciation and Amortization and Identifiable Assets (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Property and equipment additions		$ 505	$ 1,016	$ 997	$ 1,992
Depreciation and amortization		2,471	2,452	4,906	4,648
Identifiable assets		410,702		410,702		$ 419,314
Engineered Systems Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions		55	101	64	298
Depreciation and amortization		1,070	1,224	2,137	2,445
Identifiable assets		262,663		262,663		270,573
Industrial Process Solutions Segment [Member]
Segment Reporting Information [Line Items]
Property and equipment additions		172	190	362	769
Depreciation and amortization		1,073	983	2,141	1,911
Identifiable assets		136,917		136,917		135,204
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Property and equipment additions		278	725	571	925
Depreciation and amortization		328	$ 245	628	$ 292
Identifiable assets	[1]	$ 11,122		$ 11,122		$ 13,537

[1] Corporate and Other assets consist primarily of cash and income tax related assets.