Fair Value Of Assets And Liabilities (Fair Value Of Financial Instruments Held By Consolidated Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 1,397.0	$ 1,328.0	$ 1,454.5	$ 1,851.4
Available for sale investments	121.5	154.0
Foreign time deposits	28.5	26.9
Assets held for policyholders	9,230.5	8,224.2
Policyholder payables	(9,230.5)	(8,224.2)
Put option contracts	9.6	21.8
Long-term debt	(2,093.6)	(2,102.4)
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,397.0	1,328.0
Available for sale investments	121.5	154.0
Trading investments	242.2	329.6
Foreign time deposits	28.5	26.9
Assets held for policyholders	9,230.5	8,224.2
Policyholder payables	(9,230.5)	(8,224.2)
Put option contracts	9.6	21.8
UIT-related financial instruments sold, not yet purchased	(2.7)	(6.0)
Contingent consideration liability	(74.1)	(78.2)
Long-term debt	(2,093.6)	(2,102.4)
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	1,397.0	1,328.0
Available for sale investments	121.5	154.0
Trading investments	242.2	329.6
Foreign time deposits	28.5	26.9
Assets held for policyholders	9,230.5	8,224.2
Policyholder payables	(9,230.5)	(8,224.2)
Put option contracts	9.6	21.8
UIT-related financial instruments sold, not yet purchased	(2.7)	(6.0)
Contingent consideration liability	(74.1)	(78.2)
Long-term debt	$ (2,222.6)	$ (2,206.5)