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Employee Benefit Plans - Summary of Amounts Recognized on the Consolidated Balance Sheets and in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Pension Benefits |  |
Amounts recognized in accumulated other comprehensive loss [Abstract] |  |
Net gain (loss), net of taxes | $ (48.8) | $ (47.4)
Unrecognized prior service credit (cost), net of taxes | (0.1) | 0.0
Total | (48.9) | (47.4)
Other Post-retirement Benefits |  |
Amounts recognized in accumulated other comprehensive loss [Abstract] |  |
Net gain (loss), net of taxes | (3.6) | 0.2
Unrecognized prior service credit (cost), net of taxes | 0.0 | 0.0
Total | (3.6) | 0.2
Other Post-retirement Benefits | Non-qualified Plan Benefits |  |
Amounts recognized in accumulated other comprehensive loss [Abstract] |  |
Net gain (loss), net of taxes | (0.8) | (0.8)
Unrecognized prior service credit (cost), net of taxes | 0.0 | 0.0
Total | $ (0.8) | $ (0.8)

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- Definition The net of tax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan. + References No definition available. + Details
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