BUSINESS COMBINATIONS - Corporate Development and Restructuring Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Business Acquisition [Line Items]
Salaries, benefits and other compensation	$ 70,930	$ 53,138
Occupancy expense	10,792	8,460
Equipment expense	10,373	7,391
Professional fees	3,451	3,856
Data processing and operations expenses	5,359	3,385
Marketing expense	1,266	992
Other operating expense	19,015	14,378
Noninterest expenses	174,457	$ 95,619
Bryn Mawr Bank Corporation Acquisition
Business Acquisition [Line Items]
Salaries, benefits and other compensation	10,043
Occupancy expense	10,239
Equipment expense	16,586
Professional fees	8,776
Data processing and operations expenses	29
Marketing expense	1,043
Other operating expense	4,836
Noninterest expenses	$ 51,552