ACQUISITIONS - Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Net sales									$ 8,675.6	$ 8,030.5
Gross profit									2,528.3	2,102.8
Net income attributable to Wabtec shareholders									$ 485.1	$ 234.8
Diluted earnings per share
As Reported (in dollars per share)	$ 0.71	$ 0.48	$ 0.54	$ (0.04)	$ 0.36	$ 0.91	$ 0.87	$ 0.92	$ 1.84	$ 3.05	$ 2.72
Pro forma (in dollars per share)									$ 2.53	$ 1.22