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REVENUE RECOGNITION - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Jan. 01, 2018
Revenue from Contract with Customer [Abstract]        
Deferred revenue $ 11.2 $ 18.0   $ 25.5
Amortization of deferred contract acquisition costs $ 15.3 $ 20.4 $ 25.2