v3.3.1.900
Commitments, Contingencies and Concentrations (Details)
$ / shares in Units, $ in Thousands
12 Months Ended
Nov. 04, 2015
$ / shares
Dec. 31, 2015
USD ($)
broker
$ / shares
Dec. 31, 2014
USD ($)
$ / shares
Dec. 31, 2013
USD ($)
$ / shares
Loss Contingencies [Line Items]        
Gross premiums written   $ 2,662,825 $ 2,507,352 $ 2,204,159
Letters of credit outstanding   $ 76,964 82,489  
Renewal term (in years)   5 years    
Rent expense   $ 1,984 $ 2,220 $ 2,171
2016   1,395    
2017   1,126    
2018   534    
2019   491    
2020   345    
Total   $ 3,891    
Dividends declared per common share (in dollars per share) | $ / shares $ 0.14 $ 0.53 $ 0.46 $ 0.38
Letter of credit        
Loss Contingencies [Line Items]        
Collateral   $ 108,666 $ 115,151  
AmTrust Reinsurance        
Loss Contingencies [Line Items]        
Gross premiums written   1,885,974 1,610,485 $ 1,169,961
Diversified Reinsurance        
Loss Contingencies [Line Items]        
Gross premiums written   $ 776,852 $ 897,748 $ 848,790
Segment concentration risk | Gross premiums written | AmTrust Reinsurance        
Loss Contingencies [Line Items]        
Concentration risk, percentage   70.80% 64.20% 53.10%
Broker concentration risk | Gross premiums written | Diversified Reinsurance        
Loss Contingencies [Line Items]        
Concentration risk, percentage   54.60% 57.10% 57.70%
Number of major brokers | broker   3    
Broker concentration risk | Gross premiums written | Diversified Reinsurance | Top 3 Brokers        
Loss Contingencies [Line Items]        
Concentration risk, percentage   36.90% 31.60% 29.90%
Broker concentration risk | Gross premiums written | Diversified Reinsurance | Aon Benfield Group, Ltd.        
Loss Contingencies [Line Items]        
Concentration risk, percentage   17.30% 15.80% 11.90%
Broker concentration risk | Gross premiums written | Diversified Reinsurance | Marsh & McLennan Inc.        
Loss Contingencies [Line Items]        
Concentration risk, percentage   12.20% 12.00% 12.60%
Broker concentration risk | Gross premiums written | Diversified Reinsurance | U.S. RE Corporation        
Loss Contingencies [Line Items]        
Concentration risk, percentage   7.40%    
Broker concentration risk | Gross premiums written | Diversified Reinsurance | Tiger Risk Partners        
Loss Contingencies [Line Items]        
Concentration risk, percentage     3.80%  
Broker concentration risk | Gross premiums written | Diversified Reinsurance | Beach & Associates, Ltd.        
Loss Contingencies [Line Items]        
Concentration risk, percentage       5.40%
Investments in limited partnerships        
Loss Contingencies [Line Items]        
Unfunded commitment on investments in limited partnerships   $ 622 $ 736