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Fair Value Measurements (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
ASSETS: |  |
Cash equivalents | $ 15.4 | $ 7.5
Trust assets | 0.7 | 0.1
Surety bonds | 1.8 | 2.1
Derivative instruments | 21.8 | 8.2
TOTAL | 39.7 | 17.9
LIABILITIES: |  |
Contingent obligation – net | 0.0 | 0.0
Derivative instruments | 5.3 | 2.5
TOTAL | 5.3 | 2.5
Fair Value, Inputs, Level 1 [Member] |  |
ASSETS: |  |
Cash equivalents | 15.4 | 7.5
Trust assets | 0.7 | 0.1
Surety bonds | 1.8 | 2.1
Derivative instruments | 0.0 | 0.0
TOTAL | 17.9 | 9.7
LIABILITIES: |  |
Contingent obligation – net | 0.0 | 0.0
Derivative instruments | 0.0 | 0.0
TOTAL | 0.0 | 0.0
Fair Value, Inputs, Level 2 [Member] |  |
ASSETS: |  |
Cash equivalents | 0.0 | 0.0
Trust assets | 0.0 | 0.0
Surety bonds | 0.0 | 0.0
Derivative instruments | 6.1 | 3.2
TOTAL | 6.1 | 3.2
LIABILITIES: |  |
Contingent obligation – net | 0.0 | 0.0
Derivative instruments | 3.8 | 2.0
TOTAL | 3.8 | 2.0
Fair Value, Inputs, Level 3 [Member] |  |
ASSETS: |  |
Cash equivalents | 0.0 | 0.0
Trust assets | 0.0 | 0.0
Surety bonds | 0.0 | 0.0
Derivative instruments | 15.7 | 5.0
TOTAL | 15.7 | 5.0
LIABILITIES: |  |
Contingent obligation – net | 0.0 | 0.0
Derivative instruments | 1.5 | 0.5
TOTAL | $ 1.5 | $ 0.5

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