Summary of Significant Accounting Policies (Schedule of Trust Assets and Reinsurance Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents	$ 198.9		$ 157.6
Restricted securities available for sale	53.0		53.2
Accounts payable and accrued liabilities	129.9		114.4
Trust Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents	2.1		0.2
Restricted securities available for sale	53.0		53.2
Unearned Premium [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts payable and accrued liabilities	41.8		38.4
Claims Reserve [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts payable and accrued liabilities	$ 1.4	[1]	$ 1.5	[1]

[1] The claims reserve is estimated based on historical claims experience.