Supplemental Financial Information (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Apr. 30, 2021	Dec. 31, 2020
Supplemental Financial Information [Abstract]
Currency translation adjustment	$ 0.0		$ 6.5
AOCI, Derivative Qualifying as Hedge, Excluded Component, after Tax	0.0		5.6
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(0.2)		(98.2)
Other	0.0		(1.8)
Accumulated other comprehensive loss	$ (0.2)	$ 0.0	$ (87.9)

Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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- Definition

Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

+ References

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- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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- Definition

Amount, after tax, of accumulated gain (loss) from increase (decrease) in value of excluded component of derivative hedge.

+ References

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- Definition

Accumulated Other Comprehensive Income (Loss), Other, Net of Tax

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- Definition

Supplemental Financial Information [Abstract]

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