Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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LOANS - Loan Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Loans receivable, net
Gross loans, including deferred origination costs	$ 7,244,147		$ 7,415,952
Allowance for credit losses	(51,750)	$ (55,069)	(60,869)	$ (64,437)	$ (55,652)	$ (49,911)
Net loans	7,192,397		7,355,083
Commercial Portfolio Segment [Member] \| Business Lending [Member]
Loans receivable, net
Gross loans, including deferred origination costs	3,186,487		3,440,077
Allowance for credit losses	(23,417)	(27,042)	(28,190)	(24,204)	(19,489)	(19,426)
Residential Portfolio Segment [Member] \| Consumer Mortgage [Member]
Loans receivable, net
Gross loans, including deferred origination costs	2,408,499
Allowance for credit losses	(10,001)	(9,686)	(10,672)	(13,088)	(12,430)	(10,269)
Consumer Portfolio Segment [Member] \| Consumer Mortgage [Member]
Loans receivable, net
Gross loans, including deferred origination costs	2,408,499		2,401,499
Consumer Portfolio Segment [Member] \| Consumer Indirect [Member]
Loans receivable, net
Gross loans, including deferred origination costs	1,109,504		1,021,885
Allowance for credit losses	(11,103)	(11,120)	(13,696)	(15,866)	(13,694)	(13,712)
Consumer Portfolio Segment [Member] \| Consumer Direct [Member]
Loans receivable, net
Gross loans, including deferred origination costs	148,540		152,657
Allowance for credit losses	(2,548)	(2,682)	(3,207)	(4,028)	(3,737)	(3,255)
Consumer Portfolio Segment [Member] \| Home Equity [Member]
Loans receivable, net
Gross loans, including deferred origination costs	391,117		399,834
Allowance for credit losses	$ (1,796)	$ (1,543)	$ (2,222)	$ (2,690)	$ (2,484)	$ (2,129)