XML 92 R71.htm IDEA: XBRL DOCUMENT v3.10.0.1
Long-Term Debt - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Nov. 09, 2006
Debt Instrument [Line Items]        
Carrying value of surplus note $ 11,397,000 $ 12,868,000    
Principal repayments of Surplus Note 1,500,000 1,500,000 $ 1,500,000  
Surplus during the term of surplus note 50,000,000      
Interest expense $ 300,000 $ 300,000 $ 400,000  
Surplus Note        
Debt Instrument [Line Items]        
Unsecured term loan agreement       $ 25,000,000.0
Debt term 20 years      
Effective interest rate 2.89% 2.47% 1.88%  
Principal repayments of Surplus Note $ 368,000      
Maturity year of debt instrument through 2026      
Net written premium to surplus ratio 200.00%      
Gross written premium to surplus ratio 600.00%      
Surplus Note | Hurricane        
Debt Instrument [Line Items]        
Surplus and Reinsurance sufficient to cover in excess of UPCIC probable maximum loss 1-in-100 year