LOANS - Carrying Amounts of Loans Purchased and Sold (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Carrying Amounts of Loans Purchased and Sold
Purchases	$ 339,704
Sales	79,709
Business Lending [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	253,509
Sales	0
Consumer Mortgage [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	26,721
Sales	79,709
Consumer Indirect [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	13,926
Sales	0
Consumer Direct [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	5,994
Sales	0
Home Equity [Member]
Carrying Amounts of Loans Purchased and Sold
Purchases	39,554
Sales	$ 0