Significant Accounting Policies (Taxes) (Details) (State Required Premium Income Taxes [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
State Required Premium Income Taxes [Member]
Significant Accounting Policies [Line Items]
Premium taxes paid based on membership or billed premiums	$ 51.6	$ 62.1	$ 54.3