LOANS (Loans by credit quality indicator narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 10,177,385,000		$ 9,954,572,000
Allowance for credit loss	100,522,000	$ 130,172,000	$ 110,088,000	$ 131,606,000
Loans secured by residential real estate property in process of foreclosure	$ 980,000
Loans delinquent 30 to 89 days, percentage	0.10%		0.07%
Interest income on nonaccrual loans	$ 0	$ 0
Nonaccrual loans with no related allowance	27,900,000		$ 25,500,000
Nonpass | Paycheck Protection Program ("PPP")
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,200,000		$ 27,800,000
Allowance for credit loss	$ 0