XML 41 R30.htm IDEA: XBRL DOCUMENT v3.19.1
REVENUE (Summary of Contract Liabilities) (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Mar. 31, 2018
REVENUE [Abstract]      
Contract liabilities $ 817 $ 2,602 $ 13,518