Income Taxes Reconciliation of Cincinnati Global Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Valuation Allowance
Valuation allowance at January 1	$ 41
Valuation allowance at December 31	56	$ 41
Cincinnati Global
Valuation Allowance
Valuation allowance at January 1	41	0
Acquisition accounting amount	0	55
Current year operations	15	(14)
Valuation allowance at December 31	$ 56	$ 41

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

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- Definition

The amount of the valuation allowance recorded in a business combination against deductible temporary differences for which related tax benefits will be recorded as a reduction of the acquired entity's income tax expense (after such benefits are first being applied to reduce goodwill and then other noncurrent intangible assets to zero).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 740
-Section 25
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=121554379&loc=d3e9901-128506

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- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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