BUSINESS COMBINATIONS - Pro Forma Information (Details) - Bryn Mawr Bank Corporation Acquisition - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Business Acquisition [Line Items]
Net interest income	$ 139,810	$ 288,779
Provision for credit losses	(51,202)	(97,954)
Net interest income after provision for credit losses	191,012	386,733
Total noninterest income	69,984	137,647
Total noninterest expenses	132,713	264,821
Income before income taxes	128,283	259,559
Income tax provision	32,391	64,164
Net income	$ 95,892	$ 195,395
Per share data:
Weighted-average basic shares outstanding (in shares)	65,420,226	65,423,241
Dilutive shares (in shares)	317,220	294,422
Adjusted weighted-average diluted shares (in shares)	65,737,446	65,717,663
Basic earnings per common share (in dollars per share)	$ 1.47	$ 2.99
Diluted earnings per common share (in dollars per share)	$ 1.46	$ 2.97