Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Effective income tax rate, percent	30.20%	11.70%	31.30%	21.50%
Increase (decrease) in unrecognized tax benefits	$ 6.5	$ (2.4)	$ 14.4	$ (8.1)
Settlement agreement (as defined therein) with taxing authority		1,490.0		1,490.0
Decrease in U.S. federal tax liability		$ 525.0		$ 525.0

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319

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- Definition

The amount the liability recorded for the income tax examination increased or decreased in the current year/accounting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319

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- Definition

The amount of the additional liability or refund received or expected based on a final settlement with a taxing authority.

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- Definition

Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319

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