Restricted Securities Available for Sale (Schedule of Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Total restricted securities available for sale	$ 54.6	$ 53.6
Cost [Member]
Summary Of Significant Accounting Policies [Line Items]
Within one year	17.8	41.6
Over one year to five years	34.6	7.8
Over five years to ten years	2.3	4.5
Total restricted securities available for sale	54.7	53.9
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Within one year	17.8	41.6
Over one year to five years	34.6	7.8
Over five years to ten years	2.2	4.2
Total restricted securities available for sale	$ 54.6	$ 53.6