Fair Value (Reconciliation Of The Beginning And Ending Balances Of Assets Measured At Fair Value On A Recurring Basis Using Level III Inputs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 247.1	$ 193.0	$ 177.9	$ 155.5
Total gains (losses) recognized in net income	(33.0)	(15.0)	(7.8)	(17.1)
Total gains (losses) recognized in accumulated other comprehensive income	(0.3)	2.6	14.0	7.0
Purchases	23.2	10.1	61.4	56.5
Sales	(22.5)	(1.6)	(38.3)	(4.1)
Settlements	(3.2)	(5.2)	(10.5)	(17.4)
Transfers into Level III	0.6	25.4	24.8	38.5
Transfers out of Level III	(11.1)	(12.9)	(20.7)	(22.5)
Ending balance	200.8	196.4	200.8	196.4
Change in unrealized losses included in net income related to assets still held	(3.5)	(15.0)	(11.8)	(19.6)
Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	150.4	139.2	115.2	121.1
Total gains (losses) recognized in net income	(0.8)	(14.9)	(7.1)	(16.0)
Total gains (losses) recognized in accumulated other comprehensive income	(0.5)	4.9	12.2	1.8
Purchases	19.6	6.4	40.5	45.3
Sales	(20.8)	(1.6)	(27.0)	(1.6)
Settlements	(3.0)	(2.7)	(6.6)	(12.6)
Transfers into Level III	0.6	3.0	24.8	3.0
Transfers out of Level III	0	0	(6.5)	(6.7)
Ending balance	145.5	134.3	145.5	134.3
Change in unrealized losses included in net income related to assets still held	(3.5)	(14.9)	(11.1)	(16.5)
Residential Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	12.6	0	4.3
Total gains (losses) recognized in net income	0	0	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	(1.9)
Transfers into Level III	0	0	0	13.1
Transfers out of Level III	0	(12.6)	0	(15.5)
Ending balance	0	0	0	0
Change in unrealized losses included in net income related to assets still held	0	0	0	0
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3.6	0	6.5	0
Total gains (losses) recognized in net income	0	0	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0	0	0
Purchases	0	0	3.6	0
Sales	0	0	0	0
Settlements	(0.2)	(2.3)	(3.6)	(2.3)
Transfers into Level III	0	12.6	0	12.6
Transfers out of Level III	0	0	(3.1)	0
Ending balance	3.4	10.3	3.4	10.3
Change in unrealized losses included in net income related to assets still held	0	0	0	0
Other Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	17.8	5.4	14.8	3.9
Total gains (losses) recognized in net income	0	(0.1)	0	(0.1)
Total gains (losses) recognized in accumulated other comprehensive income	0.1	0.1	0.4	0.4
Purchases	3.5	0	6.5	1.6
Sales	(1.6)	0	(1.6)	0
Settlements	0	(0.2)	(0.3)	(0.6)
Transfers into Level III	0	9.8	0	9.8
Transfers out of Level III	(11.1)	(0.3)	(11.1)	(0.3)
Ending balance	8.7	14.7	8.7	14.7
Change in unrealized losses included in net income related to assets still held	0	(0.1)	0	(0.1)
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	43.1	35.8	41.4	26.2
Total gains (losses) recognized in net income	0	0	(0.7)	(1.0)
Total gains (losses) recognized in accumulated other comprehensive income	0.1	(2.4)	1.4	4.8
Purchases	0.1	3.7	10.8	9.6
Sales	(0.1)	0	(9.7)	(2.5)
Settlements	0	0	0	0
Transfers into Level III	0	0	0	0
Transfers out of Level III	0	0	0	0
Ending balance	43.2	37.1	43.2	37.1
Change in unrealized losses included in net income related to assets still held	0	0	(0.7)	(3.0)
Long Term Receivable [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	32.2	0	0	0
Total gains (losses) recognized in net income	(32.2)	0	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers into Level III	0	0	0	0
Transfers out of Level III	0	0	0	0
Ending balance	0	0	0	0
Change in unrealized losses included in net income related to assets still held	$ 0	$ 0	$ 0	$ 0