Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Feb. 28, 2019	Dec. 31, 2018
Income Tax Contingency
Tax at statutory rate, percentage	21.00%	21.00%	21.00%	21.00%
Effective income tax rate reduction due to tax rate change		8.10%		6.00%
Unrecognized Tax Benefits	$ 34		$ 34			$ 34
Cincinnati Global
Income Tax Contingency
Net deferred tax assets due to acquisition					$ 59
Deferred tax assets valuation allowance due to acquisition					$ 55
Net deferred tax assets	44		44
Deferred tax assets valuation allowance	43		43
Operating loss carryforwards	$ 161		$ 161