Acquisitions - Pro Forma Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Combinations [Abstract]
Net sales	$ 2,001.7	$ 1,994.8	$ 6,317.8	$ 5,891.2
Gross profit	615.4	575.7	1,376.4	1,595.8
Net income attributable to Wabtec shareholders	$ 103.3	$ 120.7	$ 358.5	$ 195.4
Diluted earnings per share
As Reported (in dollars per share)	$ 0.48	$ 0.91	$ 1.11	$ 2.70
Pro forma (in dollars per share)	$ 0.55	$ 0.63	$ 1.87	$ 1.02