Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator
Net income (loss) attributable to Wabtec shareholders	$ 111.6	$ (4.5)
Less: dividends declared - common shares    and non-vested restricted stock	(23.0)	(11.7)
Undistributed earnings	$ 88.6	$ (16.2)
Percentage allocated to common shareholders (as a percent)	99.70%	99.70%
Add: dividends declared - common shares	$ 22.9	$ 11.6
Undistributed earnings allocated to common shareholders	88.3	(16.2)
Numerator for diluted earnings per    common share	$ 111.2	$ (4.6)
Denominator
Basic weighted average common shares outstanding (in shares)	190.8	121.2
Assumed conversion of dilutive stock-based compensation plans (in shares)	0.6	0.0
Denominator for diluted earnings per common share - adjusted weighted average shares and assumed conversion (in shares)	191.4	121.2
Net income attributable to Wabtec shareholders per common share
Basic (in dollars per share)	$ 0.58	$ (0.04)
Diluted (in dollars per share)	$ 0.58	$ (0.04)
Basic weighted-average common shares outstanding and non-vested restricted stock expected to vest (in shares)	191.4	121.6