CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	0.2	0.3	0.6	0.9
Postretirement Benefit Plans:
Amortization of prior service cost	(0.1)	(0.2)	(0.3)	(0.5)
Other Comprehensive Income Reclassification Of Defined Benefit Postretirement Plans Net Gain Loss Recognized In Net Periodic Benefit Cost Tax	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Noncontrolling Interest	0.0	0.1	0.1	(0.3)
Pension Plan [Member]
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax	$ 0.3	$ 0.5	$ 1.9	$ 0.6

-- None. No documentation exists for this element. --

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Tax effect on adjustment out of other comprehensive income for prior service costs recognized as a component of net periodic postretirement benefit cost during the period.

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Other Comprehensive Income Reclassification Of Defined Benefit Postretirement Plans Net Gain Loss Recognized In Net Periodic Benefit Cost Tax

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Amount of tax expense (benefit) for increase (decrease) to other comprehensive income from settlement and curtailment gain (loss) of defined benefit plan.

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Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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Amount before tax of other comprehensive income (loss) attributable to noncontrolling interests.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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