FAIR VALUE - Items Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Total
Cash equivalents:
Derivative assets (Note 15)	$ 2.9	$ 1.2
Total assets	203.1	193.0
Liabilities:
Derivative liabilities (Note 15)	1.9	4.7
Total liabilities	39.0	38.4
Bank time deposits with original maturities of three months or less | Total
Cash equivalents:
Bank time deposits with original maturities of three months or less	163.3	159.1
Diversified investments associated with the Executive Stock Unit Program (ESUP) | Total
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	36.9	32.7
Liabilities associated with the ESUP | Total
Liabilities:
Total liabilities	37.1	33.7
Level 1
Cash equivalents:
Derivative assets (Note 15)	0.0	0.0
Total assets	36.9	32.7
Liabilities:
Derivative liabilities (Note 15)	0.0	0.0
Total liabilities	37.1	33.7
Level 1 | Bank time deposits with original maturities of three months or less
Cash equivalents:
Bank time deposits with original maturities of three months or less	0.0	0.0
Level 1 | Diversified investments associated with the Executive Stock Unit Program (ESUP)
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	36.9	32.7
Level 1 | Liabilities associated with the ESUP
Liabilities:
Total liabilities	37.1	33.7
Level 2
Cash equivalents:
Derivative assets (Note 15)	2.9	1.2
Total assets	166.2	160.3
Liabilities:
Derivative liabilities (Note 15)	1.9	4.7
Total liabilities	1.9	4.7
Level 2 | Bank time deposits with original maturities of three months or less
Cash equivalents:
Bank time deposits with original maturities of three months or less	163.3	159.1
Level 2 | Diversified investments associated with the Executive Stock Unit Program (ESUP)
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	0.0	0.0
Level 2 | Liabilities associated with the ESUP
Liabilities:
Total liabilities	0.0	0.0
Level 3
Cash equivalents:
Derivative assets (Note 15)	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Derivative liabilities (Note 15)	0.0	0.0
Total liabilities	0.0	0.0
Level 3 | Bank time deposits with original maturities of three months or less
Cash equivalents:
Bank time deposits with original maturities of three months or less	0.0	0.0
Level 3 | Diversified investments associated with the Executive Stock Unit Program (ESUP)
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	0.0	0.0
Level 3 | Liabilities associated with the ESUP
Liabilities:
Total liabilities	$ 0.0	$ 0.0