Segment Information (Reconciliation Of Reportable Segments Operating Gain To Income Before Income Tax Expense Included In The Consolidated Statements Of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting [Abstract]
Reportable segments operating gain	$ 1,078.1	$ 1,221.9	$ 4,148.7	$ 4,313.3
Net investment income	200.9	161.2	566.9	515.5
Net realized gains (losses) on financial instruments	88.8	(11.9)	(23.8)	126.9
Other-than-temporary impairment losses recognized in income	(11.0)	(19.1)	(103.6)	(54.9)
Interest expense	(172.9)	(164.8)	(545.7)	(473.3)
Amortization of other intangible assets	(47.4)	(60.0)	(145.7)	(172.6)
Gain (loss) on extinguishment of debt	0.0	2.3	0.0	1.8
Income before income tax expense	$ 1,136.5	$ 1,129.6	$ 3,896.8	$ 4,256.7