| **Income Taxes (Narrative) (Details) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |        |
|----------------------------------------------------------------|----------------|----------------|--------|
||
| **Income Tax Contingency**                                     |           |           |   |   |   |
| Tax at statutory rate, percentage                              | 21.00%         | 21.00%         | 21.00% | 21.00% |   |
| Unrecognized Tax Benefits                                      | $ 34           |           | $ 34   |   | $ 34 |
| Deferred tax assets valuation allowance                        | 0              |           | 0      |   | $ 0 |
| Cincinnati Global                                              |           |           |   |   |   |
| **Income Tax Contingency**                                     |           |           |   |   |   |
| Change in deferred tax assets                                  | 15             |           | 13     |   |   |
| Change in deferred tax valuation allowance                     | 15             |           | 13     |   |   |
| Net deferred tax assets                                        | 54             |           | 54     |   |   |
| Deferred tax assets valuation allowance                        | 54             |           | 54     |   |   |
| Operating loss carryforwards                                   | $ 178          |           | $ 178  |   |   |

| X                                                                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Increase (Decrease) of deferred tax assets
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.
+ References
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| - Definition
Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of domestic federal statutory tax rate applicable to pretax income (loss).
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| - Definition
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.
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No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.
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| - Definition
Amount of unrecognized tax benefits.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.
+ References
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