BUSINESS COMBINATIONS - Schedule of Pro Forma Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combinations [Abstract]
Net interest income and noninterest income	$ 202,324	$ 192,254
Net income	19,750	47,853
Net income available to common shareholders	$ 19,750	$ 47,853
Income per common share available to common shareholders – basic (in dollars per share)	$ 0.29	$ 0.69
Income per common share available to common shareholders – diluted (in dollars per share)	$ 0.28	$ 0.69
Average number of shares outstanding, basic (in shares)	69,248	69,548
Average number of shares outstanding, diluted (in shares)	69,502	69,638