LOANS - Carrying Amounts of Loans Purchased and Sold (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Carrying Amounts of Loans Purchased and Sold
Purchases	$ 0
Sales	17,803
Commercial Portfolio Segment [Member] | Business Lending [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	0
Sales	848
Residential Portfolio Segment [Member] | Consumer Mortgage [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	0
Sales	16,955
Consumer Portfolio Segment [Member] | Consumer Indirect [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	0
Sales	0
Consumer Portfolio Segment [Member] | Consumer Direct [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	0
Sales	0
Consumer Portfolio Segment [Member] | Home Equity [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	0
Sales	$ 0