ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY INFORMATION - Schedule of Allowance for Loan Losses and Loan Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Allowance for credit losses
Beginning balance	$ 141,970	$ 132,418	$ 94,507	$ 228,804
Initial allowance on acquired PCD loans			26,103
Charge-offs	(7,498)	(10,861)	(16,316)	(23,415)
Recoveries	4,273	4,624	7,214	8,515
Provision (credit)	7,450	(21,310)	34,687	(109,033)
Ending balance	146,195	104,871	146,195	104,871
Period-end allowance allocated to:
Loans evaluated on an individual basis	5,348	2,255	5,348	2,255
Loans evaluated on a collective basis	140,847	102,616	140,847	102,616
Period-end loan balances:
Loans evaluated on an individual basis	46,456	39,711	46,456	39,711
Loans evaluated on a collective basis	11,655,916	7,971,988	11,655,916	7,971,988
Gross loans	11,702,372	8,011,699	11,702,372	8,011,699	$ 7,882,055
Reverse mortgage, fair value	3,000	7,500	3,000	7,500	3,900
Bryn Mawr Bank Corporation Acquisition
Allowance for credit losses
Initial allowance on acquired PCD loans			26,100
Period-end loan balances:
Loans purchased with no credit deterioration			23,500
Commercial | Commercial and industrial
Allowance for credit losses
Beginning balance	60,921	87,203	49,967	150,875
Initial allowance on acquired PCD loans			22,614
Charge-offs	(5,120)	(7,612)	(11,308)	(19,176)
Recoveries	3,194	4,031	4,667	6,550
Provision (credit)	889	(17,804)	(6,056)	(72,431)
Ending balance	59,884	65,818	59,884	65,818
Period-end allowance allocated to:
Loans evaluated on an individual basis	5,348	2,247	5,348	2,247
Loans evaluated on a collective basis	54,536	63,571	54,536	63,571
Period-end loan balances:
Loans evaluated on an individual basis	21,565	24,375	21,565	24,375
Loans evaluated on a collective basis	3,147,913	2,204,139	3,147,913	2,204,139
Gross loans	3,169,478	2,228,514	3,169,478	2,228,514	2,270,319
Commercial | Owner-occupied commercial
Allowance for credit losses
Beginning balance	5,510	6,181	4,574	9,615
Initial allowance on acquired PCD loans			595
Charge-offs	0	(38)	(179)	(83)
Recoveries	4	41	271	146
Provision (credit)	489	(1,260)	742	(4,754)
Ending balance	6,003	4,924	6,003	4,924
Period-end allowance allocated to:
Loans evaluated on an individual basis	0	0	0	0
Loans evaluated on a collective basis	6,003	4,924	6,003	4,924
Period-end loan balances:
Loans evaluated on an individual basis	1,713	2,071	1,713	2,071
Loans evaluated on a collective basis	1,786,878	1,337,589	1,786,878	1,337,589
Gross loans	1,788,591	1,339,660	1,788,591	1,339,660	1,341,707
Commercial | Commercial mortgages
Allowance for credit losses
Beginning balance	23,663	16,099	11,623	31,071
Initial allowance on acquired PCD loans			2,684
Charge-offs	(544)	0	(581)	0
Recoveries	101	198	223	242
Provision (credit)	(1,686)	(3,054)	7,585	(18,070)
Ending balance	21,534	13,243	21,534	13,243
Period-end allowance allocated to:
Loans evaluated on an individual basis	0	8	0	8
Loans evaluated on a collective basis	21,534	13,235	21,534	13,235
Period-end loan balances:
Loans evaluated on an individual basis	9,483	2,708	9,483	2,708
Loans evaluated on a collective basis	3,270,896	1,985,276	3,270,896	1,985,276
Gross loans	3,280,379	1,987,984	3,280,379	1,987,984	1,881,510
Commercial | Construction
Allowance for credit losses
Beginning balance	5,058	3,512	1,903	12,190
Initial allowance on acquired PCD loans			71
Charge-offs	0	(2,473)	0	(2,473)
Recoveries	653	0	653	0
Provision (credit)	788	1,068	3,872	(7,610)
Ending balance	6,499	2,107	6,499	2,107
Period-end allowance allocated to:
Loans evaluated on an individual basis	0	0	0	0
Loans evaluated on a collective basis	6,499	2,107	6,499	2,107
Period-end loan balances:
Loans evaluated on an individual basis	5,360	2,184	5,360	2,184
Loans evaluated on a collective basis	1,022,843	760,462	1,022,843	760,462
Gross loans	1,028,203	762,646	1,028,203	762,646	687,213
Residential
Allowance for credit losses
Beginning balance	4,988	3,293	3,352	6,893
Initial allowance on acquired PCD loans			61
Charge-offs	0	0	(186)	0
Recoveries	207	34	737	629
Provision (credit)	(377)	(326)	854	(4,521)
Ending balance	4,818	3,001	4,818	3,001
Period-end allowance allocated to:
Loans evaluated on an individual basis	0	0	0	0
Loans evaluated on a collective basis	4,818	3,001	4,818	3,001
Period-end loan balances:
Loans evaluated on an individual basis	6,451	5,877	6,451	5,877
Loans evaluated on a collective basis	752,142	568,804	752,142	568,804
Gross loans	758,593	574,681	758,593	574,681	542,733
Consumer
Allowance for credit losses
Beginning balance	41,830	16,130	23,088	18,160
Initial allowance on acquired PCD loans			78
Charge-offs	(1,834)	(738)	(4,062)	(1,683)
Recoveries	114	320	663	948
Provision (credit)	7,347	66	27,690	(1,647)
Ending balance	47,457	15,778	47,457	15,778
Period-end allowance allocated to:
Loans evaluated on an individual basis	0	0	0	0
Loans evaluated on a collective basis	47,457	15,778	47,457	15,778
Period-end loan balances:
Loans evaluated on an individual basis	1,884	2,496	1,884	2,496
Loans evaluated on a collective basis	1,675,244	1,115,718	1,675,244	1,115,718
Gross loans	$ 1,677,128	$ 1,118,214	$ 1,677,128	$ 1,118,214	$ 1,158,573