Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle
Income tax benefit for difference in tax rate	$ 0	$ 0	$ 50
Unrecognized Tax Benefits	34	34	34	$ 0
Income taxes refund received	0	94	$ 0
Net deferred tax assets, valuation allowance	56	41
Deferred tax benefit due to tax rate change			19.90%
Cincinnati Global
New Accounting Pronouncements or Change in Accounting Principle
Net deferred tax assets	56
Net deferred tax assets, valuation allowance	56	41	$ 0
Current year operations	15	(14)
Cincinnati Global
New Accounting Pronouncements or Change in Accounting Principle
Increase (Decrease) of deferred tax assets	15
Current year operations	15
Cincinnati Global | Geographic Distribution, Foreign [Member]
New Accounting Pronouncements or Change in Accounting Principle
Operating Loss Carryforwards	108	127
Cincinnati Global | Geographic Distribution, Domestic [Member]
New Accounting Pronouncements or Change in Accounting Principle
Operating Loss Carryforwards	$ 26	$ 20