STOCKHOLDERS' EQUITY - Issuance of common stock, IPO (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2018 $ / shares shares	Sep. 30, 2018 USD ($) $ / shares
Issuance of stock
Proceeds from issuance of common stock, net of issuance costs | $			$ 101,607
IPO
Issuance of stock
Share price (in dollars per share) | $ / shares	$ 16.00	$ 16.00	$ 16.00
Proceeds from issuance of common stock, net of issuance costs | $	$ 99,507
Common Stock
Issuance of stock
Shares issued (in shares) | shares		6,900,000
Common Stock | IPO
Issuance of stock
Shares issued (in shares) | shares	6,900,000