• Filing Date: 2018-03-07
  • Form Type: 10-K
  • Description: Annual report
v3.8.0.1
Investments (Other-than-temporary Impairment) - Additional Information (Detail)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
Securities
Dec. 31, 2016
USD ($)
Securities
Dec. 31, 2015
USD ($)
Securities
Schedule of Investments [Line Items]      
Other-than-temporary impairment losses $ 1,467 $ 2,482 $ 4,681
Other-than-temporary impairment losses related to additional loss $ 1,116 $ 2,252 $ 5,275
Number of securities in an unrealized loss position | Securities 135 134  
Number of securities had been in an unrealized loss position for 12 months or longer | Securities 22 20  
Fixed-Maturity Securities [Member]      
Schedule of Investments [Line Items]      
Other-than-temporary impairment losses, number of securities sold | Securities 4    
Other-than-temporary impairment losses, number of securities | Securities   4 2
Other-than-temporary impairment losses $ 428 $ 1,565 $ 705
Other-than-temporary impairment losses related to additional loss   1,335  
Impairment loss recorded in other comprehensive income   $ 230  
Other-than-temporary impairment losses related to credit losses     111
Accumulated other-than-temporary impairment losses related to non-credit losses     $ 594
Equity Securities [Member]      
Schedule of Investments [Line Items]      
Other-than-temporary impairment losses, number of securities | Securities 1 9 17
Other-than-temporary impairment losses related to additional loss $ 1,039 $ 917 $ 4,570
Two Fixed Maturities [Member]      
Schedule of Investments [Line Items]      
Fixed-maturity securities with cumulative credit losses $ 475    
Corporate Bonds [Member]      
Schedule of Investments [Line Items]      
Accumulated other-than-temporary impairment losses related to non-credit losses   $ 76