SCHEDULE I SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Summary of investments other than investments in related parties
Cost	$ 7,102.0	[1]
Carrying Value	7,428.9	[1]
Fair Value	7,428.9	[1]
Fixed maturity investments
Summary of investments other than investments in related parties
Cost	5,265.9	[1]
Carrying Value	5,266.8	[1]
Fair Value	5,266.8	[1]
US Government and agency obligations
Summary of investments other than investments in related parties
Cost	365.5
Carrying Value	362.5
Fair Value	362.5
Debt securities issued by corporations
Summary of investments other than investments in related parties
Cost	2,330.7
Carrying Value	2,347.2
Fair Value	2,347.2
Mortgage-backed and asset-backed securities
Summary of investments other than investments in related parties
Cost	2,027.3
Carrying Value	2,014.5
Fair Value	2,014.5
Municipal obligations
Summary of investments other than investments in related parties
Cost	18.3
Carrying Value	17.9
Fair Value	17.9
Foreign government, agency and provincial obligations
Summary of investments other than investments in related parties
Cost	444.2
Carrying Value	439.9
Fair Value	439.9
Redeemable preferred stocks
Summary of investments other than investments in related parties
Cost	79.9
Carrying Value	84.8
Fair Value	84.8
Short-term investments
Summary of investments other than investments in related parties
Cost	635.9
Carrying Value	635.9
Fair Value	635.9
Common equity securities
Summary of investments other than investments in related parties
Cost	890.2
Carrying Value	1,156.8
Fair Value	1,156.8
Banks, trust and insurance companies
Summary of investments other than investments in related parties
Cost	274.2
Carrying Value	360.4
Fair Value	360.4
Public utilities
Summary of investments other than investments in related parties
Cost	32.1
Carrying Value	34.3
Fair Value	34.3
Industrial, miscellaneous and other
Summary of investments other than investments in related parties
Cost	583.9
Carrying Value	762.1
Fair Value	762.1
Convertible fixed maturity investments
Summary of investments other than investments in related parties
Cost	71.7
Carrying Value	80.5
Fair Value	80.5
Other long-term investments
Summary of investments other than investments in related parties
Cost	238.3
Carrying Value	288.9
Fair Value	288.9
Discontinued Operations
Summary of investments other than investments in related parties
Investments reclassified to assets held for sale	$ 236.3		$ 338.1	$ 111.8

[1] Carrying value and fair value includes $236.3 classified as assets held for sale relating to discontinued operations. See Note 21 - “Discontinued Operations”.