FAIR VALUE - Items Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Total
Cash equivalents:
Derivative assets	$ 18.5	$ 7.9
Total assets	154.9	210.3
Liabilities:
Derivative liabilities	0.9	2.5
Total liabilities	48.9	47.9
Total | Diversified investments associated with the (ESUP)
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	48.4	45.9
Total | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESUP	48.0	45.4
Total | Bank time deposits with original maturities of three months or less
Cash equivalents:
Bank time deposits with original maturities of three months or less	88.0	156.5
Level 1
Cash equivalents:
Derivative assets	0.0	0.0
Total assets	48.4	45.9
Liabilities:
Derivative liabilities	0.0	0.0
Total liabilities	48.0	45.4
Level 1 | Diversified investments associated with the (ESUP)
Cash equivalents:
Diversified investments associated with the Executive Stock Unit Program (ESUP)	48.4	45.9
Level 1 | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESUP	48.0	45.4
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 2
Cash equivalents:
Derivative assets	18.5	7.9
Total assets	106.5	164.4
Liabilities:
Derivative liabilities	0.9	2.5
Total liabilities	0.9	2.5
Level 2 | Diversified investments associated with the (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:
Liabilities associated with the ESUP	0.0	0.0
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	88.0	156.5
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 | Diversified investments associated with the (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:
Liabilities associated with the ESUP	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