BUSINESS COMBINATIONS - Corporate Development and Restructuring Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Business Acquisition [Line Items]
Salaries, benefits and other compensation	$ 68,189	$ 52,408	$ 139,119	$ 105,546
Occupancy expense	9,902	8,083	20,694	16,543
Equipment expense	10,388	7,338	20,761	14,729
Professional fees	5,273	3,401	8,724	7,257
Data processing and operations expenses	5,288	3,444	10,647	6,829
Marketing expense	1,637	1,286	2,903	2,278
Total corporate development and restructuring expenses	134,049	$ 96,032	308,506	$ 191,651
Bryn Mawr Bank Corporation Acquisition
Business Acquisition [Line Items]
Salaries, benefits and other compensation	2,215		12,258
Occupancy expense	1,121		11,360
Equipment expense	3,104		19,690
Professional fees	3,106		11,883
Data processing and operations expenses	71		99
Marketing expense	1,931		2,973
Other operating expense, net	(1,221)		3,616
Total corporate development and restructuring expenses	$ 10,327		$ 61,879