Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
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
Reduction of deferred tax assets	6
Reduction of deferred tax valuation allowance	6
Net deferred tax assets	35
Deferred tax assets valuation allowance	35
Operating loss carryforwards	$ 118