Fair Value Measurements - Recurring Fair Value Measurements (Details) - Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
ASSETS:
Cash equivalents	$ 9.3	$ 14.2
Trust assets	0.6	0.1
Derivative instruments	229.0	42.8
TOTAL	238.9	57.1
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0.0	0.0
Derivative instruments	30.1	146.2
TOTAL	30.1	146.2
Level 1 [Member]
ASSETS:
Cash equivalents	9.3	14.2
Trust assets	0.6	0.1
Derivative instruments	0.0	0.0
TOTAL	9.9	14.3
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0.0	0.0
Derivative instruments	0.0	0.0
TOTAL	0.0	0.0
Level 2 [Member]
ASSETS:
Cash equivalents	0.0	0.0
Trust assets	0.0	0.0
Derivative instruments	225.7	42.6
TOTAL	225.7	42.6
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0.0	0.0
Derivative instruments	27.8	140.9
TOTAL	27.8	140.9
Level 3 [Member]
ASSETS:
Cash equivalents	0.0	0.0
Trust assets	0.0	0.0
Derivative instruments	3.3	0.2
TOTAL	3.3	0.2
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0.0	0.0
Derivative instruments	2.3	5.3
TOTAL	$ 2.3	$ 5.3