XML 65 R60.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Financial Instruments - Summary of Bond Activity (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]    
Fair value at beginning of period $ 56,556 $ 51,101
Purchases 27,216 18,426
Sales (1,686) (1,793)
Maturities and calls (22,272) (10,445)
Decrease in bond premium (460) (377)
Fair market value adjustment 1,305 (356)
Fair value at end of period $ 60,659 $ 56,556