Business Combination (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2009	Dec. 07, 2009	Oct. 02, 2009	Jul. 31, 2009
Business Acquisition [Line Items]
Amount of net income attributable to non-controlling interest of subsidiary for the period October 2, 2009 to December 7, 2009	$ 4.3
[ParisReMember]
Business Acquisition [Line Items]
Percentage of voting interests acquired		100.00%	83.00%
Percentage of voting interests ownership prior to acquisition				6.00%
Percentage of voting interests acquired in a transaction			77.00%
Aggregate purchase price paid by the Company to acquire 100% of the outstanding Paris Re common shares and warrants	1,979.7
Total identifiable net assets acquired, at fair value	1,953.7
Goodwill recorded in connection with acquisition	26
Amount of net income attributable to non-controlling interest of subsidiary for the period October 2, 2009 to December 7, 2009	$ 4.3