Fair Value Measurements (Changes in Level 3 Financial Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 11.4	$ 5.5
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Total gains or losses for the period:
Realized in net income	68.6	5.9
Unrealized in accumulated other comprehensive income	0	0
Purchases, issues, sales and settlements:
Purchases	0	0
Issuances	0	0
Sales	(0.2)	0
Settlements	(9.7)	0
Ending balance	70.1	11.4
Change in unrealized gains (losses) included in net income for assets held at the end of the reporting period	0	0
Available-For-Sale Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	0.2	0.2
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Total gains or losses for the period:
Realized in net income	0	0
Unrealized in accumulated other comprehensive income	0	0
Purchases, issues, sales and settlements:
Purchases	0	0
Issuances	0	0
Sales	(0.2)	0
Settlements	0	0
Ending balance	0	0.2
Change in unrealized gains (losses) included in net income for assets held at the end of the reporting period	0	0
Embedded Contractual Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	11.2	5.3
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Total gains or losses for the period:
Realized in net income	5.7	5.9
Unrealized in accumulated other comprehensive income	0	0
Purchases, issues, sales and settlements:
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(9.7)	0
Ending balance	7.2	11.2
Change in unrealized gains (losses) included in net income for assets held at the end of the reporting period	0	0
State-Sponsored Health Plans Settlement Account Deficit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	0
Transfers into Level 3	0
Transfers out of Level 3	0
Total gains or losses for the period:
Realized in net income	62.9
Unrealized in accumulated other comprehensive income	0
Purchases, issues, sales and settlements:
Purchases	0
Issuances	0
Sales	0
Settlements	0
Ending balance	62.9
Change in unrealized gains (losses) included in net income for assets held at the end of the reporting period	$ 0