Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator
Net income attributable to Wabtec shareholders	$ 87,739	$ 67,399	$ 260,521	$ 213,313
Less: dividends declared - common shares and non-vested restricted stock	(11,586)	(11,518)	(34,682)	(30,693)
Undistributed earnings	$ 76,153	$ 55,881	$ 225,839	$ 182,620
Percentage allocated to common shareholders (as a percent)	99.70%	99.70%	99.70%	99.40%
Undistributed earnings allocated to common shareholders	$ 75,925	$ 55,713	$ 225,161	$ 181,524
Add: dividends declared - common shares	11,552	11,485	34,579	30,508
Numerator for basic and diluted earnings per common share	$ 87,477	$ 67,198	$ 259,740	$ 212,032
Denominator
Basic weighted average common shares outstanding (in shares)	96,208	95,709	95,935	95,163
Assumed conversion of dilutive stock-based compensation plans (in shares)	429	607	501	645
Denominator for diluted earnings per common share - adjusted weighted average shares and assumed conversion (in shares)	96,637	96,316	96,436	95,808
Net income attributable to Wabtec shareholders per common share
Basic (in dollars per share)	$ 0.91	$ 0.70	$ 2.71	$ 2.23
Diluted (in dollars per share)	$ 0.91	$ 0.70	$ 2.70	$ 2.22
Basic weighted-average common shares outstanding and non-vested restricted stock expected to vest (in shares)	96,495	95,983	96,221	95,740