STOCK-BASED COMPENSATION - Aggregate (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock-based compensation
Aggregate stock-based compensation charges	$ 0.9	$ 1.0
Stock Option
Stock-based compensation
Unrecognized stock-based compensation expense	$ 3.7
Weighted average period of recognition	2 years 7 months 6 days
Restricted Stock Units (RSUs)
Stock-based compensation
Unrecognized stock-based compensation expense	$ 4.2
Weighted average period of recognition	2 years 2 months 12 days

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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