Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
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