RETIREMENT AND POSTRETIREMENT PLANS - 401(K) Plan - (Details) - 401 K Plan	12 Months Ended
	Dec. 31, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Maximum contribution by employee, for the calendar year	$ 19,500
Percentage of match for first 1% of employee contributions	100.00%
Percentage of employee contribution on which 100% match by employer	1.00%
Percentage of match on next 1% of employee contributions	50.00%
Common stock within the accounts of participants	$ 9,700,000
Total expense recognized as a component of salaries and employee benefits expense	$ 2,000,000.0
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of employee contribution on which 50% match by employer	6.00%
Maximum Percentage of participating employee contribution	3.50%