Fair Value Of Assets And Liabilities (Fair Value Of Financial Instruments Held By Consolidated Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,581.3	$ 1,851.4	$ 1,590.7	$ 1,514.2
Available for sale investments	161.2	233.2
Foreign time deposits	27.0	24.7
Assets held for policyholders	7,387.5	6,051.5
Policyholder payables	(7,387.5)	(6,051.5)
Put option contracts	17.6	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	1,581.3	1,851.4
Available for sale investments	161.2	233.2
Trading investments	411.1	402.7
Foreign time deposits	27.0	24.7
Assets held for policyholders	7,387.5	6,051.5
Policyholder payables	(7,387.5)	(6,051.5)
Put option contracts	17.6	1.4
UIT-related financial instruments sold, not yet purchased	(0.2)	(2.5)
Contingent consideration liability	(80.7)	(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	1,581.3	1,851.4
Available for sale investments	161.2	233.2
Trading investments	411.1	402.7
Foreign time deposits	27.0	24.7
Assets held for policyholders	7,387.5	6,051.5
Policyholder payables	(7,387.5)	(6,051.5)
Put option contracts	17.6	1.4
UIT-related financial instruments sold, not yet purchased	(0.2)	(2.5)
Contingent consideration liability	(80.7)	(83.9)
Long-term debt	$ (2,279.5)	$ (2,161.3)