v3.19.3
REVENUE - Deferred Revenue (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Jun. 30, 2019
Dec. 31, 2018
Jun. 30, 2018
Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                
Deferred revenue $ 45,263 $ 33,614 $ 45,263 $ 33,614 $ 44,812 $ 36,451 $ 27,155 $ 1,590
Deferred revenue arising from business combination 0 22,800 0 22,800        
Revenue recognized in the period from amounts included in deferred revenue at the beginning of the period $ 12,656 $ 10,165 $ 28,280 $ 1,539        
Balances without adoption of ASC 606                
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                
Deferred revenue         44,812 36,451 27,155 5,893
Accounting Standards Update 2014-09 | Effect of change                
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                
Deferred revenue         $ 0 $ 0 $ 0 $ (4,303)