Fair Value Of Assets And Liabilities (Fair Value Of Financial Instruments Held By Consolidated Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,454.5	$ 1,851.4	$ 1,219.7	$ 1,514.2
Available for sale investments	191.0	233.2
Foreign time deposits	28.8	24.7
Assets held for policyholders	6,578.3	6,051.5
Policyholder payables	(6,578.3)	(6,051.5)
Put option contracts	10.9	1.4
Long-term debt	(2,073.2)	(2,072.8)
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,454.5	1,851.4
Available for sale investments	191.0	233.2
Trading investments	347.3	402.7
Foreign time deposits	28.8	24.7
Assets held for policyholders	6,578.3	6,051.5
Policyholder payables	(6,578.3)	(6,051.5)
Put option contracts	10.9	1.4
UIT-related financial instruments sold, not yet purchased	(1.7)	(2.5)
Contingent consideration liability	(77.2)	(83.9)
Long-term debt	(2,073.2)	(2,072.8)
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,454.5	1,851.4
Available for sale investments	191.0	233.2
Trading investments	347.3	402.7
Foreign time deposits	28.8	24.7
Assets held for policyholders	6,578.3	6,051.5
Policyholder payables	(6,578.3)	(6,051.5)
Put option contracts	10.9	1.4
UIT-related financial instruments sold, not yet purchased	(1.7)	(2.5)
Contingent consideration liability	(77.2)	(83.9)
Long-term debt	$ (2,200.1)	$ (2,161.3)