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

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Amount of cost to be recognized for option under share-based payment arrangement.

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STOCK-BASED COMPENSATION - Aggregate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based compensation
Aggregate stock-based compensation charges	$ 3.8	$ 3.6	$ 1.9
Stock Option
Stock-based compensation
Unrecognized stock-based compensation expense	$ 4.1
Weighted average period of recognition	2 years 9 months 18 days
Restricted Stock Units (RSUs)
Stock-based compensation
Unrecognized stock-based compensation expense	$ 5.0
Weighted average period of recognition	2 years 4 months 24 days