SEGMENT INFORMATION - THIRD PARTY NET SALES, EXCLUDING PRECIOUS METAL CONTENT (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Major Customer [Line Items]
Net sales	$ 1,042.1	$ 992.7	$ 1,998.2	$ 1,893.2
Technologies & Equipment
Revenue, Major Customer [Line Items]
Net sales	548.8	532.8	1,057.1	1,011.8
Consumables
Revenue, Major Customer [Line Items]
Net sales	493.3	459.9	941.1	881.4
Operating Segments
Revenue, Major Customer [Line Items]
Net sales	1,032.7	983.0	1,978.5	1,872.4
Operating Segments | Technologies & Equipment
Revenue, Major Customer [Line Items]
Net sales	539.4	523.1	1,037.4	991.0
Operating Segments | Consumables
Revenue, Major Customer [Line Items]
Net sales	493.3	459.9	941.1	881.4
Segment Reconciling Items
Revenue, Major Customer [Line Items]
Net sales	$ 9.4	$ 9.7	$ 19.7	$ 20.8