STOCK-BASED COMPENSATION - Adoption of ASU No. 2016-09 (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
STOCK-BASED COMPENSATION.
Benefit (provision) for income taxes	$ 1,134	$ (2,354)	$ 1,043	$ (4,060)
Retained earnings	$ 316,245		$ 316,245		$ 318,572

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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