Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21.00%		35.00%
Tax Adjustments, Settlements, and Unusual Provisions		$ 193.0
Effective tax rate	22.70%	8.80%	107.50%
Tax benefit from the reduction in net deferred tax liabilities		$ 0.2	$ 882.0	$ 882.3
DRD constituting non-taxable investment income	$ 11.0	15.0	46.0
Non-taxable investment income	12.0	19.0	47.0
Income (loss) from domestic operations	$ (1,280.0)	$ 1,844.0	$ 1,118.0
Income Taxes, Reconciling Items, Percent Of Income Tax Expense (Benefit)	5.00%