Revenue - Net Sales and (Loss) Income before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 127,427	$ 110,550	$ 242,504	$ 214,066
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	(2,152)	(2,336)	(1,204)	(6,913)
Forged and Cast Mill Rolls [Member]
Disaggregation Of Revenue [Line Items]
Net sales	74,927	61,720	142,415	125,972
Forged Engineered Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	28,059	26,637	54,479	44,088
Heat Exchange Coils [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,325	6,514	13,726	13,435
Centrifugal Pumps [Member]
Disaggregation Of Revenue [Line Items]
Net sales	9,389	9,976	17,764	20,160
Air Handling Systems [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,727	5,703	14,120	10,411
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	65,601	60,590	124,152	116,092
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	(1,347)	(5,805)	(3,522)	(10,691)
Foreign
Disaggregation Of Revenue [Line Items]
Net sales	61,826	49,960	118,352	97,974
(Loss) Income Before Income Taxes and Equity Income in Joint Venture	$ (805)	$ 3,469	$ 2,318	$ 3,778