ACQUISITIONS Acquisitions Textuals (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Jan. 26, 2017
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 0.0	$ 113.7
Goodwill	$ 895.7			$ 886.8
Axtone Railway Components Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Jan. 26, 2017
Business Acquisition, Name of Acquired Entity	Axtone Railway Components (Axtone)
Payments to Acquire Businesses, Net of Cash Acquired		$ 123.1
Revenue of Acquired Entity for Last Annual Period			$ 72.0
Goodwill					$ 86.0