Other Intangible Assets Textuals (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense related to finite-lived intangible assets	$ 18.9	$ 20.1	$ 14.0
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average period (in years)	12 years 3 months 18 days
Proprietary technology [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average period (in years)	13 years 2 months 12 days
Patents and Other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average period (in years)	11 years 3 months 18 days
Axtone Railway Components Acquisition [Member] | Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average period (in years)	12 years
Finite-lived Intangible Assets Acquired	$ 7.6
Axtone Railway Components Acquisition [Member] | Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted average period (in years)	10 years
Finite-lived Intangible Assets Acquired	$ 2.3
Industrial Process
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 4.1