EARNINGS PER SHARE - Summary of Basic Earnings Per Share (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2017	Mar. 31, 2017 USD ($) $ / shares shares
Earnings Per Share [Abstract]
Net income | $	$ 23,292		$ 16,638
Weight average common shares (in shares) | shares	45,506		37,895
Basic earnings per share (in dollars per share) | $ / shares	$ 0.51		$ 0.44
Stock split conversion ratio		36