Fair Value Of Assets And Liabilities (Fair Value Of Financial Instruments Held By Consolidated Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,048.6	$ 1,147.7	$ 1,631.5
Foreign time deposits	26.5	28.1
Policyholder payables	(10,442.4)	(11,384.8)
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,048.6	1,147.7
Equity investments	466.3	283.2
Foreign time deposits	26.5	28.1
Assets held for policyholders	10,442.4	11,384.8
Policyholder payables	(10,442.4)	(11,384.8)
Contingent consideration liability	(49.9)	(40.9)
Long-term debt	$ (2,490.2)	$ (2,418.2)