LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loan Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Loans receivable, net
Gross loans, including deferred origination costs	$ 8,543,607	$ 7,373,639
Allowance for credit losses	(60,363)	(49,869)
Net loans	8,483,244	7,323,770
Business lending
Loans receivable, net
Gross loans, including deferred origination costs	3,494,425	3,075,904
Consumer mortgage
Loans receivable, net
Gross loans, including deferred origination costs	2,975,521	2,556,114
Consumer indirect
Loans receivable, net
Gross loans, including deferred origination costs	1,461,235	1,189,749
Consumer direct
Loans receivable, net
Gross loans, including deferred origination costs	179,399	153,811
Home equity
Loans receivable, net
Gross loans, including deferred origination costs	433,027	398,061
Commercial Portfolio Segment | Business lending
Loans receivable, net
Gross loans, including deferred origination costs	3,494,425	3,075,904
Residential Portfolio Segment | Consumer mortgage
Loans receivable, net
Gross loans, including deferred origination costs	2,975,521	2,556,114
Residential Portfolio Segment | Home equity
Loans receivable, net
Gross loans, including deferred origination costs	433,027	398,061
Consumer Portfolio Segment | Consumer indirect
Loans receivable, net
Gross loans, including deferred origination costs	1,461,235	1,189,749
Consumer Portfolio Segment | Consumer direct
Loans receivable, net
Gross loans, including deferred origination costs	$ 179,399	$ 153,811