Fair Value Of Assets And Liabilities (Fair Value Of Financial Instruments Held By Consolidated Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,446.2	$ 1,851.4	$ 1,465.7	$ 1,514.2
Available for sale investments	188.5	233.2
Foreign time deposits	15.0	24.7
Assets held for policyholders	6,620.4	6,051.5
Policyholder payables	(6,620.4)	(6,051.5)
Put option contracts	14.1	1.4
Long-term debt	(2,072.7)	(2,072.8)
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,446.2	1,851.4
Available for sale investments	188.5	233.2
Trading investments	396.8	402.7
Foreign time deposits	15.0	24.7
Assets held for policyholders	6,620.4	6,051.5
Policyholder payables	(6,620.4)	(6,051.5)
Put option contracts	14.1	1.4
UIT-related financial instruments sold, not yet purchased	(1.5)	(2.5)
Contingent consideration liability	(89.3)	(83.9)
Long-term debt	(2,072.7)	(2,072.8)
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,446.2	1,851.4
Available for sale investments	188.5	233.2
Trading investments	396.8	402.7
Foreign time deposits	15.0	24.7
Assets held for policyholders	6,620.4	6,051.5
Policyholder payables	(6,620.4)	(6,051.5)
Put option contracts	14.1	1.4
UIT-related financial instruments sold, not yet purchased	(1.5)	(2.5)
Contingent consideration liability	(89.3)	(83.9)
Long-term debt	$ (2,266.9)	$ (2,161.3)