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PROPERTY AND EQUIPMENT - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Property Plant And Equipment [Abstract]            
Depreciation expense $ 2.3 $ 2.3 $ 7.1 $ 7.5 $ 9.9 $ 10.9