LONG-TERM DEBT - Surety Bonds, Letters of Credit and Guarantees (Narrative) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Surety bonds
Guarantor Obligations [Line Items]
Outstanding surety bonds, commercial standby letters of credit and bank guarantees	$ 77.0
Commercial standby letters of credit
Guarantor Obligations [Line Items]
Outstanding surety bonds, commercial standby letters of credit and bank guarantees	164.6
Bank guarantees
Guarantor Obligations [Line Items]
Outstanding surety bonds, commercial standby letters of credit and bank guarantees	37.6
Cash secured bank guarantees
Guarantor Obligations [Line Items]
Outstanding surety bonds, commercial standby letters of credit and bank guarantees	$ 17.4