Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Income Tax Contingency
Tax at statutory rate, percentage	21.00%	21.00%
Unrecognized Tax Benefits	$ 34		$ 34
Deferred tax assets valuation allowance	0		0
Cincinnati Global
Income Tax Contingency
Decrease in deferred tax assets	3
Decrease in deferred tax valuation allowance	3
Net deferred tax assets	50
Deferred tax assets valuation allowance	50
Cincinnati Global | United States
Income Tax Contingency
Operating loss carryforwards	6		8
Cincinnati Global | United Kingdom
Income Tax Contingency
Operating loss carryforwards	$ 130		$ 130