XML 49 R69.htm IDEA: XBRL DOCUMENT v3.19.3
Fair Value of Financial Instruments - Summary of Changes in Fair Value of Investments (Detail) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Fair Value Disclosures [Abstract]    
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales $ (14) $ (12)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning Balance 686 648
Purchases and adjustments 123 64
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 0 (29)
Investment Income 11 8
Ending Balance $ 806 $ 679