Revenue - Net Sales and (Loss) Income before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 112,216	$ 103,886	$ 354,720	$ 317,952
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	(5,656)	(3,707)	(6,860)	(10,620)
Forged and Cast Mill Rolls [Member]
Disaggregation Of Revenue [Line Items]
Net sales	64,983	63,677	207,398	189,649
Forged Engineered Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	23,107	18,002	77,586	62,090
Heat Exchange Coils [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,132	8,279	20,858	21,714
Centrifugal Pumps [Member]
Disaggregation Of Revenue [Line Items]
Net sales	9,790	7,522	27,554	27,682
Air Handling Systems [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,204	6,406	21,324	16,817
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	53,713	55,940	177,865	172,032
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	(3,208)	(4,263)	(6,730)	(14,954)
Foreign
Disaggregation Of Revenue [Line Items]
Net sales	58,503	47,946	176,855	145,920
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	$ (2,448)	$ 556	$ (130)	$ 4,334