Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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
Reduction of deferred tax assets	4		2
Reduction of deferred tax valuation allowance	4		2
Net deferred tax assets	39		39
Deferred tax assets valuation allowance	39		39
Operating loss carryforwards	$ 140		$ 140