Revenue and Income (Loss) Before Income Taxes - Net Sales and Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation Of Revenue [Line Items]
Net sales	$ 92,428	$ 74,778	$ 179,228	$ 165,841
Income (loss) before income taxes	2,596	1,365	3,291	3,184
Forged and Cast Mill Rolls [Member]
Disaggregation Of Revenue [Line Items]
Net sales	65,974	47,770	124,140	113,422
Forged Engineered Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	5,054	2,690	10,239	5,802
Heat Exchange Coils [Member]
Disaggregation Of Revenue [Line Items]
Net sales	5,898	6,832	11,955	13,380
Centrifugal Pumps [Member]
Disaggregation Of Revenue [Line Items]
Net sales	8,000	10,064	18,042	18,308
Air Handling Systems [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,502	7,422	14,852	14,929
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	43,892	39,737	88,374	79,787
Income (loss) before income taxes	(1,210)	(91)	(1,271)	(1,431)
Foreign [Member]
Disaggregation Of Revenue [Line Items]
Net sales	48,536	35,041	90,854	86,054
Income (loss) before income taxes	$ 3,806	$ 1,456	$ 4,562	$ 4,615