Summary of Significant Accounting Policies (Schedule of Trust Assets and Reinsurance Liabilities) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents		$ 232.8	$ 167.4
Restricted securities available for sale		47.0	48.3
Accounts payable and accrued liabilities		133.9	127.8
Trust Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents		0.8	0.8
Restricted securities available for sale		47.0	48.3
Unearned Premium [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts payable and accrued liabilities		34.7	35.2
Claims Reserve [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts payable and accrued liabilities	[1]	$ 1.1	$ 1.2

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