Income Taxes (Summary Of Deferred Tax Assets And Deferred Tax Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets
Policyholder and separate account reserves	$ 808.1	$ 1,063.5
Net operating loss carryforwards	53.8	147.0
Investments, net	91.1	57.3
Credit carryforwards	33.0	38.0
Employee and post-retirement benefits	25.5	32.8
Compensation related	29.9	31.6
Capital loss carryforwards	9.8	3.1
Other	54.1	123.3
Total deferred tax assets	1,105.3	1,496.6
Less valuation allowance	(27.6)	(76.6)
Deferred tax assets, net of valuation allowance	1,077.7	1,420.0
Deferred Tax Liabilities
Deferred acquisition costs	(1,211.2)	(1,472.0)
Net unrealized appreciation on securities	(413.3)	(274.0)
Intangible assets	(105.8)	(67.5)
Total deferred tax liabilities	(1,730.3)	(1,813.5)
Net deferred income tax liabilities	$ (652.6)	$ (393.5)