v2.4.0.6
Fair Value Measurement of Financial Assets and Financial Liabilities on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets $ 2,050,918
Fair Value of liabilities 304,834
U.S. treasury securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 46,863
U.S. government agencies
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 54,381
Municipal bonds
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 273,052
Commercial mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 10,118
Agency, residential mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 367,430
Non-agency, residential mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 7,224
Equity securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 25,830
Short term investments
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 33,134
Other investments
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 15,103
Life settlement contracts
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 151,092
Equity securities sold but not yet purchased, market
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 58
Fixed maturity securities sold but not yet purchased , market
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 56,920
Securities sold under agreements to repurchase, at contract value
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 231,919
Life settlement contract profit commission
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 11,465
Derivatives
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 4,472
Corporate Bonds | Finance
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 754,629
Corporate Bonds | Industrial
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 272,761
Corporate Bonds | Utilities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 39,301
Fair Value, Inputs, Level 1
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 105,827
Fair Value of liabilities 58
Fair Value, Inputs, Level 1 | U.S. treasury securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 46,863
Fair Value, Inputs, Level 1 | Equity securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 25,830
Fair Value, Inputs, Level 1 | Short term investments
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 33,134
Fair Value, Inputs, Level 1 | Equity securities sold but not yet purchased, market
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 58
Fair Value, Inputs, Level 2
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 1,778,896
Fair Value of liabilities 288,839
Fair Value, Inputs, Level 2 | U.S. government agencies
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 54,381
Fair Value, Inputs, Level 2 | Municipal bonds
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 273,052
Fair Value, Inputs, Level 2 | Commercial mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 10,118
Fair Value, Inputs, Level 2 | Agency, residential mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 367,430
Fair Value, Inputs, Level 2 | Non-agency, residential mortgage backed securities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 7,224
Fair Value, Inputs, Level 2 | Fixed maturity securities sold but not yet purchased , market
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 56,920
Fair Value, Inputs, Level 2 | Securities sold under agreements to repurchase, at contract value
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 231,919
Fair Value, Inputs, Level 2 | Corporate Bonds | Finance
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 754,629
Fair Value, Inputs, Level 2 | Corporate Bonds | Industrial
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 272,761
Fair Value, Inputs, Level 2 | Corporate Bonds | Utilities
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 39,301
Fair Value, Inputs, Level 3
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 166,195
Fair Value of liabilities 15,937
Fair Value, Inputs, Level 3 | Other investments
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 15,103
Fair Value, Inputs, Level 3 | Life settlement contracts
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair value of assets 151,092
Fair Value, Inputs, Level 3 | Life settlement contract profit commission
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities 11,465
Fair Value, Inputs, Level 3 | Derivatives
 
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]  
Fair Value of liabilities $ 4,472