Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
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
Decrease in deferred tax assets	8		11
Decrease in deferred tax valuation allowance	8		11
Net deferred tax assets	42		42
Deferred tax assets valuation allowance	42		42
Cincinnati Global | United States
Income Tax Contingency
Operating loss carryforwards	6		6		8
Cincinnati Global | United Kingdom
Income Tax Contingency
Operating loss carryforwards	$ 125		$ 125		$ 130