FAIR VALUE - Items Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Total
Cash equivalents:
Derivative assets	$ 2.2	$ 1.2
Total assets	231.7	193.0
Liabilities:
Derivative liabilities	1.4	4.7
Total liabilities	39.9	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	191.1	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)	38.4	32.7
Liabilities associated with the ESUP | Total
Liabilities:
Total liabilities	38.5	33.7
Level 1
Cash equivalents:
Derivative assets	0.0	0.0
Total assets	38.4	32.7
Liabilities:
Derivative liabilities	0.0	0.0
Total liabilities	38.5	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)	38.4	32.7
Level 1 | Liabilities associated with the ESUP
Liabilities:
Total liabilities	38.5	33.7
Level 2
Cash equivalents:
Derivative assets	2.2	1.2
Total assets	193.3	160.3
Liabilities:
Derivative liabilities	1.4	4.7
Total liabilities	1.4	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	191.1	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	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Derivative liabilities	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