Summary Of Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Thousands
Jan. 01, 2018
Dec. 31, 2017
Minimum    
Significant Accounting Policies [Line Items]    
Traditional life products, life reserve interest assumptions range, maximum   2.30%
Maximum    
Significant Accounting Policies [Line Items]    
Traditional life products, life reserve interest assumptions range, maximum   6.00%
Accounting Standards Update 2018-02 | Subsequent Event    
Significant Accounting Policies [Line Items]    
Reclassification from AOCI to retained earning tax effect $ (2,279)  
Increase to AOCI $ 2,279  
Long Term Care | Minimum    
Significant Accounting Policies [Line Items]    
Traditional life products, life reserve interest assumptions range, maximum   5.00%
Long Term Care | Maximum    
Significant Accounting Policies [Line Items]    
Traditional life products, life reserve interest assumptions range, maximum   6.00%