Acquisitions - Pro Forma Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combinations [Abstract]
Net sales	$ 1,929.9	$ 2,069.2
Gross profit	578.7	454.3
Net income attributable to Wabtec shareholders	$ 111.6	$ (53.7)
Diluted earnings per share
As Reported (in dollars per share)	$ 0.58	$ (0.04)
Pro forma (in dollars per share)	$ 0.58	$ (0.44)