OTHER COMPREHENSIVE LOSS - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ 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
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Interest expense, net									$ (219.1)	$ (112.2)	$ (77.9)
Income tax expense									(120.3)	(75.9)	(89.8)
Net income attributable to Wabtec shareholders	$ 135.7	$ 91.1	$ 104.1	$ (4.2)	$ 34.4	$ 87.7	$ 84.4	$ 88.4	326.7	294.9	$ 262.3
Reclassification out of Accumulated Other Comprehensive Income | Amortization of initial net obligation and prior service cost
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income, net									(1.5)	(1.5)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of net loss (gain)
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income, net									4.4	4.3
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post Retirement Benefit Plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Other income, net									2.9	2.8
Income tax expense									(0.8)	(0.7)
Net income attributable to Wabtec shareholders									$ 2.1	2.1
Reclassification out of Accumulated Other Comprehensive Income | Derivative contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Interest expense, net										4.9
Income tax expense										(1.2)
Net income attributable to Wabtec shareholders										$ 3.7