XML 73 R58.htm IDEA: XBRL DOCUMENT v3.20.4
Revenue (Advance Billings) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Revenue from Contract with Customer [Abstract]    
Advance billings, current $ 106,498 $ 92,464
Advance billings, noncurrent 1,277 $ 1,245
Increase (decrease)    
Advance billings, current 14,034  
Advance billings, noncurrent $ 32