Related Party Transactions - Additional Information (Detail)	3 Months Ended				3 Months Ended		3 Months Ended		3 Months Ended				3 Months Ended				3 Months Ended
	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Mar. 31, 2014 Non-Life Run-Off [Member] USD ($)	Dec. 31, 2013 Non-Life Run-Off [Member] USD ($)	Mar. 31, 2014 Global Atlantic Financial Group [Member] USD ($)	Dec. 31, 2013 Global Atlantic Financial Group [Member] USD ($)	Mar. 31, 2014 Global Atlantic Financial Group [Member] Non-Life Run-Off [Member] USD ($)	Dec. 31, 2013 Global Atlantic Financial Group [Member] Non-Life Run-Off [Member] USD ($)	Mar. 31, 2014 Trident [Member] USD ($) Investment	Jul. 31, 2012 Trident [Member]	Dec. 31, 2013 Trident [Member] USD ($)	Mar. 31, 2014 Stone Point Capital LLC [Member] USD ($)	Mar. 31, 2014 Sound Point Capital [Member] USD ($)	Mar. 31, 2013 Sound Point Capital [Member] USD ($)	Dec. 31, 2013 Sound Point Capital [Member] USD ($)	Mar. 31, 2014 Sound Point Capital [Member] Mr. Carey [Member]	Mar. 31, 2014 Goldman Sachs [Member] USD ($) Investment	Mar. 31, 2014 Goldman Sachs [Member] Non-Voting Convertible Common Stock [Member]	Mar. 31, 2014 Hastings Insurance Group Limited [Member] USD ($) Company	Mar. 31, 2014 Hastings Insurance Group Limited [Member] GBP (£) Company	Mar. 31, 2014 Goldman Sachs Affiliates [Member]
Related Party Transaction [Line Items]
Percentage of Company's voting ordinary shares acquired									8.50%
Related party transaction, shares acquired										1,350,000
Shareholders agreement period	90 days								90 days
Noncontrolling interest	$ 227,320,000	$ 222,000,000							$ 361,100,000
Fair value of the investments in funds									108,900,000		87,700,000	20,000,000	21,900,000		21,600,000		3,100,000
Investments of funds affiliated with entities									2								1
Net realized and unrealized gains													400,000	300,000
Indirect ownership interest																4.00%
Ordinary shares					22.00%												4.20%	100.00%
Investment in indirect non-voting interests of affiliated companies																			20,800,000	12,500,000
Indirect non-voting investments in number of companies																			2	2
Affiliates interest percentage																					50.00%
Reinsurance recoverable	1,256,230,000	1,363,819,000	1,196,918,000	1,298,992,000	302,000,000	340,800,000
Reinsurance recoverable secured in a trust account							229,300,000	256,100,000
Reinsurance recoverable major reinsurer							10.00%
Reinsurance recoverable unsecured by trust account							$ 72,700,000	$ 84,700,000