SEGMENT INFORMATION - THIRD PARTY NET SALES, EXCLUDING PRECIOUS METAL CONTENT (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue, Major Customer [Line Items]
Net sales	$ 1,009.4	$ 1,042.1	$ 1,955.6	$ 1,998.2
Technologies & Equipment
Revenue, Major Customer [Line Items]
Net sales	558.4	553.2	1,079.2	1,063.3
Consumables
Revenue, Major Customer [Line Items]
Net sales	451.0	488.9	876.4	934.9
Operating Segments
Revenue, Major Customer [Line Items]
Net sales	1,000.5	1,032.7	1,935.5	1,978.5
Operating Segments | Technologies & Equipment
Revenue, Major Customer [Line Items]
Net sales	558.4	553.2	1,079.2	1,063.3
Operating Segments | Consumables
Revenue, Major Customer [Line Items]
Net sales	442.1	479.5	856.3	915.2
Segment Reconciling Items
Revenue, Major Customer [Line Items]
Net sales	$ 8.9	$ 9.4	$ 20.1	$ 19.7