Business Segments - Business Segment Net Sales and Income (Loss) before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from External Customer [Line Items]
Net sales	$ 115,077	$ 103,516
Income (loss) before Income Taxes	948	(4,577)
Forged and Cast Mill Rolls [Member]
Revenue from External Customer [Line Items]
Net sales	67,488	64,252
Forged Engineered Products [Member]
Revenue from External Customer [Line Items]
Net sales	26,420	17,451
Heat Exchange Coils [Member]
Revenue from External Customer [Line Items]
Net sales	6,401	6,921
Centrifugal Pumps [Member]
Revenue from External Customer [Line Items]
Net sales	8,375	10,184
Air Handling Systems [Member]
Revenue from External Customer [Line Items]
Net sales	6,393	4,708
U.S. [Member]
Revenue from External Customer [Line Items]
Net sales	58,551	55,502
Income (loss) before Income Taxes	(2,175)	(4,886)
Foreign
Revenue from External Customer [Line Items]
Net sales	56,526	48,014
Income (loss) before Income Taxes	3,123	309
Operating Segments [Member]
Revenue from External Customer [Line Items]
Net sales	115,077	103,516
Income (loss) before Income Taxes	3,135	1,958
Operating Segments [Member] | Forged and Cast Engineered Products [Member]
Revenue from External Customer [Line Items]
Net sales	93,908	81,702
Income (loss) before Income Taxes	876	(723)
Operating Segments [Member] | Air and Liquid Processing [Member]
Revenue from External Customer [Line Items]
Net sales	21,169	21,814
Income (loss) before Income Taxes	2,259	2,681
Other Expense, Including Corporate Costs - Net [Member]
Revenue from External Customer [Line Items]
Income (loss) before Income Taxes	$ (2,187)	$ (6,535)