• Filing Date: 2019-03-08
  • Form Type: 10-K
  • Description: Annual report
v3.10.0.1
Investments (Net Investment Income) - Additional Information (Detail)
$ in Thousands
Dec. 31, 2018
USD ($)
Bank
Accounts
Dec. 31, 2017
USD ($)
Bank
Accounts
Schedule of Investments [Line Items]    
Cash and cash equivalents $ 239,458 $ 255,884
Deposits representing cash and cash equivalents in percentage 75.40% 34.10%
Number of national banks | Bank 3 3
Number of custodial accounts | Accounts 2 3
Federal Deposit Insurance Corporation's coverage limit for insured deposit accounts $ 250 $ 250
Custodial Accounts [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents 73,511 38,543
Bank Deposits [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents $ 180,508 $ 87,092