XML 49 R26.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Allowance for doubtful accounts (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Allowance for Doubtful Accounts Receivable    
Allowance for doubtful accounts balance - beginning of year $ 20 $ 20
Additions to the allowance for doubtful accounts 0 0
Deductions against the allowance for doubtful accounts 0 0
Allowance for doubtful accounts balance - end of year $ 20 $ 20