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
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 177.9	$ 155.5
Total gains (losses) recognized in net income	18.0	0.9
Total gains (losses) recognized in accumulated other comprehensive income	(2.5)	(1.3)
Purchases	18.3	10.0
Sales	(2.8)	(2.5)
Settlements	(5.7)	(10.9)
Transfers into Level III	0	13.1
Transfers out of Level III	(6.5)	(2.9)
Ending balance	196.7	161.9
Change in unrealized losses included in net income related to assets still held	(4.3)	(1.4)
Corporate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	115.2	121.1
Total gains (losses) recognized in net income	(3.3)	0.3
Total gains (losses) recognized in accumulated other comprehensive income	3.1	(0.6)
Purchases	9.3	9.6
Sales	(1.7)	0
Settlements	(2.1)	(9.1)
Transfers into Level III	0	0
Transfers out of Level III	(6.5)	0
Ending balance	114.0	121.3
Change in unrealized losses included in net income related to assets still held	(4.0)	0
Residential Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	4.3
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	0	(1.6)
Transfers into Level III	0	13.1
Transfers out of Level III	0	(2.9)
Ending balance	0	12.9
Change in unrealized losses included in net income related to assets still held	0	0
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6.5	0
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	(3.4)	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	3.1	0
Change in unrealized losses included in net income related to assets still held	0	0
Other Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	14.8	3.9
Total gains (losses) recognized in net income	0	0
Total gains (losses) recognized in accumulated other comprehensive income	0.2	0.2
Purchases	0	0
Sales	0	0
Settlements	(0.2)	(0.2)
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	14.8	3.9
Change in unrealized losses included in net income related to assets still held	0	0
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	41.4	26.2
Total gains (losses) recognized in net income	(0.3)	0.6
Total gains (losses) recognized in accumulated other comprehensive income	(5.8)	(0.9)
Purchases	9.0	0.4
Sales	(1.1)	(2.5)
Settlements	0	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	43.2	23.8
Change in unrealized losses included in net income related to assets still held	(0.3)	(1.4)
Long Term Receivable [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	0
Total gains (losses) recognized in net income	21.6	0
Total gains (losses) recognized in accumulated other comprehensive income	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level III	0	0
Transfers out of Level III	0	0
Ending balance	21.6	0
Change in unrealized losses included in net income related to assets still held	$ 0