STOCK-BASED COMPENSATION - Stock option activity (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	10,834
Exercised (in shares) | shares	(1,510)
Ending balance (in shares) | shares	9,324
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 18.59
Exercised (in dollars per share) | $ / shares	21.15
Ending balance (in dollars per share) | $ / shares	$ 18.17
Weighted Average Remaining Contractual Term (years)
Outstanding	2 months 12 days
Aggregate Intrinsic Value (in millions)
Ending balance | $	$ 0.7