COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Aug. 15, 2019 USD ($)	Jan. 31, 2019 USD ($)	Sep. 08, 2017 USD ($)	Dec. 31, 2019 claim
Settled Litigation | Siemens Industry, Inc.
Loss Contingencies [Line Items]
Damages award to plaintiff	$ 14.1
Pending Litigation
Loss Contingencies [Line Items]
Pending litigation cases | claim				0
Threatened Litigation | Denver Transit Installation of Constant Wireless Crossings | Subsidiaries
Loss Contingencies [Line Items]
Alleged damages			$ 36.8
Positive Train Control Patents | Settled Litigation | Siemens Industry, Inc.
Loss Contingencies [Line Items]
Damages award to plaintiff		$ 5.6
End of Train Patents | Settled Litigation | Siemens Industry, Inc.
Loss Contingencies [Line Items]
Damages award to plaintiff		$ 1.1