FAIR VALUE - Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Cash equivalents:
Derivative asset, statement of financial position [extensible enumeration]	Assets, Current, Sundry	Assets, Current, Sundry
Liabilities:
Derivative liability, statement of financial position [extensible enumeration]	Liabilities, Noncurrent, Other current liabilities	Liabilities, Noncurrent, Other current liabilities
Fair Value, Measurements, Recurring | Total
Cash equivalents:
Derivative assets (Note 13)	$ 6.1	$ 2.9
Total assets	184.3	174.7
Liabilities:
Derivative liabilities (Note 13)	6.5	5.9
Total liabilities	55.4	49.9
Fair Value, Measurements, Recurring | Total | Diversified investments associated with the ESU program
Cash equivalents:
Diversified investments associated with the ESU program	47.9	42.8
Fair Value, Measurements, Recurring | Total | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESU program	48.9	44.0
Fair Value, Measurements, Recurring | 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	130.3	129.0
Fair Value, Measurements, Recurring | Level 1
Cash equivalents:
Derivative assets (Note 13)	0.0	0.0
Total assets	47.9	42.8
Liabilities:
Derivative liabilities (Note 13)	0.0	0.0
Total liabilities	48.9	44.0
Fair Value, Measurements, Recurring | Level 1 | Diversified investments associated with the ESU program
Cash equivalents:
Diversified investments associated with the ESU program	47.9	42.8
Fair Value, Measurements, Recurring | Level 1 | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESU program	48.9	44.0
Fair Value, Measurements, Recurring | 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
Fair Value, Measurements, Recurring | Level 2
Cash equivalents:
Derivative assets (Note 13)	6.1	2.9
Total assets	136.4	131.9
Liabilities:
Derivative liabilities (Note 13)	6.5	5.9
Total liabilities	6.5	5.9
Fair Value, Measurements, Recurring | Level 2 | Diversified investments associated with the ESU program
Cash equivalents:
Diversified investments associated with the ESU program	0.0	0.0
Fair Value, Measurements, Recurring | Level 2 | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESU program	0.0	0.0
Fair Value, Measurements, Recurring | 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	130.3	129.0
Fair Value, Measurements, Recurring | Level 3
Cash equivalents:
Derivative assets (Note 13)	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Derivative liabilities (Note 13)	0.0	0.0
Total liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Level 3 | Diversified investments associated with the ESU program
Cash equivalents:
Diversified investments associated with the ESU program	0.0	0.0
Fair Value, Measurements, Recurring | Level 3 | Liabilities associated with the ESUP
Liabilities:
Liabilities associated with the ESU program	0.0	0.0
Fair Value, Measurements, Recurring | 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