ACQUISITIONS - Narrative (Detail) - USD ($) $ / shares in Units, $ in Millions					3 Months Ended	12 Months Ended
	Sep. 12, 2019	Aug. 09, 2019	Feb. 25, 2019	Mar. 22, 2018	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 06, 2019	Apr. 30, 2019	Feb. 22, 2019
Business Acquisition [Line Items]
Common stock, shares outstanding (in shares)						191,699,193	96,614,946
Preferred stock, shares outstanding (in shares)						0	0
Acquisition payments						$ 10,115.7	$ 58.9	$ 1,006.2
Common stock, shares issued (in shares)						226,947,180	132,349,534
Preferred stock, shares issued (in shares)						0	0
Purchase price						$ 2,996.4	$ 51.2	$ 945.3
Goodwill						8,360.6	2,396.5
Common Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)									3,515,500
General Electric Company
Business Acquisition [Line Items]
Acquisition payments							$ 2,885.0
Common stock, shares issued (in shares)							19,018,207
Preferred stock, shares issued (in shares)							10,000
General Electric Company | General Electric Company
Business Acquisition [Line Items]
Common stock, shares issued (in shares)							46,763,975
Annax GmbH
Business Acquisition [Line Items]
Acquisition payments					$ 10.1
Purchase price				$ 45.2
Goodwill				38.5
Goodwill expected to be deductible for taxes				0.0
Acquired intangible assets				11.7
Annax GmbH | Trade names
Business Acquisition [Line Items]
Acquired intangible assets				3.8
Annax GmbH | Customer relationships
Business Acquisition [Line Items]
Acquired intangible assets				$ 7.5
Useful life of customer relationships (in years)				20 years
GE Transportation
Business Acquisition [Line Items]
Consideration transferred			$ 2,875.0
Acquisition payments			470.0
Business combination, consideration transferred			$ 10,300.0
Purchase price per share (in euros per share)											$ 73.36
Change in estimated fair values for assets acquired						63.0
Revenues						3,800.0
Operating income						358.0
GE Transportation | General Electric Company
Business Acquisition [Line Items]
Percentage of outstanding shares transferred			9.90%
GE Transportation | GE and Pre-Merger Holders
Business Acquisition [Line Items]
Percentage of outstanding shares transferred			49.20%
GE Transportation | SpinCo Class B Preferred Stock
Business Acquisition [Line Items]
Acquisition payments			$ 10.0
GE Transportation | Convertible Preferred Stock
Business Acquisition [Line Items]
Shares issuable (in shares)			10,000
GE Transportation | Convertible Preferred Stock | General Electric Company
Business Acquisition [Line Items]
Percentage of outstanding shares transferred			15.00%
GE Transportation | General Electric Company | SpinCo Common Stock
Business Acquisition [Line Items]
Common stock, shares outstanding (in shares)			8,700,000,000
GE Transportation | General Electric Company | SpinCo Class A Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)			15,000
GE Transportation | General Electric Company | SpinCo Class B Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)			10,000
GE Transportation | General Electric Company | SpinCo Class C Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)			1
GE Transportation | General Electric Company | Series A Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)									8,780
GE Transportation | General Electric Company | Common Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)									25,300,000
Number of shares issued in transaction (in shares)	2,048,515	16,969,656
GE Transportation | Pre-merger Wabtec Stockholders
Business Acquisition [Line Items]
Percentage of outstanding shares transferred			50.80%
GE Transportation | Wabtec | SpinCo Class B Preferred Stock
Business Acquisition [Line Items]
Preferred stock, shares outstanding (in shares)			10,000
GET Brazil
Business Acquisition [Line Items]
Noncontrolling interest acquired										$ 56.2
General Electric Company
Business Acquisition [Line Items]
Noncontrolling interest acquired			$ 86.8
Change in estimated fair values for assets acquired						(92.1)
Change in estimated fair value for liabilities acquired						$ 129.1
Other noncurrent liabilities			652.9
Goodwill			5,987.5
General Electric Company | Customer Contracts [Member]
Business Acquisition [Line Items]
Other noncurrent liabilities			$ 504.7