Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended														3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Blue Water Trusts	Dec. 31, 2013 Blue Water Trusts	Mar. 31, 2014 MUSIC Trust	Dec. 31, 2013 MUSIC Trust	Mar. 31, 2014 Reinsurance Trust	Dec. 31, 2013 Reinsurance Trust	Mar. 31, 2014 FL Trust	Dec. 31, 2013 FL Trust	Mar. 31, 2014 Lloyd's Capital Trust	Dec. 31, 2013 Lloyd's Capital Trust	Mar. 31, 2014 Premiums Trust Funds	Dec. 31, 2013 Premiums Trust Funds	Mar. 31, 2014 Fixed maturity investments	Mar. 31, 2013 Fixed maturity investments	Mar. 31, 2013 Cash and cash equivalents	Mar. 31, 2014 Equity securities	Mar. 31, 2013 Equity securities	Mar. 31, 2013 Other investments
Net Investment Income
Investment income	$ 15.3	$ 18.4													$ 14.7	$ 18.0	$ 0.1	$ 0.6	$ 0.2	$ 0.1
Investment expenses	(2.4)	(2.0)
Net investment income	12.9	16.4
Assets Held in Trust
Fair value of all assets held in the trust			307.9	164.7	30.1	32.0	338.6	337.7	26.2	26.1	160.1	160.2	327.4	326.4
Sales and Maturities of Investments
Sales of investments	2,091.3	1,447.1
Maturities, calls and paydowns of investments	73.8	126.5
Non-cash exchanges or involuntary sales of investment securities	0	0
Pending Securities Litigation
Amount to be returned, if Plaintiffs fully prevail connection with Tribune LBO suits	$ 4.4