Amount and Nature of Net Assets Restricted from Payment of Dividends (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	$ 520,886		$ 519,201
Insurance
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	12,605	[1]	17,226	[1]
Insurance | Fixed maturities
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	11,105		11,728
Insurance | Short-term investments
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	290		290
Insurance | Cash
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	1,210		5,208
Lloyd's
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	508,281	[2]	501,975	[2]
Lloyd's | Fixed maturities
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	398,808		428,142
Lloyd's | Short-term investments
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	108,485		72,984
Lloyd's | Cash
Restricted Assets And Liabilities Relating To Securitization [Line Items]
Total Restricted Net Assets	$ 988		$ 849

[1] The restricted net assets for the Insurance Companies primarily consist of fixed maturities on deposit with various state insurance departments. The cash as of December 31, 2012 and 2011, as presented in the table above, was on deposit with a U.K. bank to comply with the regulatory requirements of the Prudential Regulation Authority for the underwriting activities of the U.K. Branch.

[2] The restricted net assets for the Lloyd's Operations consists of fixed maturities and cash held in trust for the benefit of syndicate policyholders and short term investments primarily consisting of overseas deposits in various countries with Lloyd's to support underwriting activities in those countries.