SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Estimated Useful Life of Different Fixed Asset Classes (Details) - Maximum	12 Months Ended
	Dec. 31, 2020
Bank Buildings
Property Plant And Equipment [Line Items]
Estimated useful life	40 years
Equipment
Property Plant And Equipment [Line Items]
Estimated useful life	10 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful life	7 years
Software
Property Plant And Equipment [Line Items]
Estimated useful life	5 years
Automobiles
Property Plant And Equipment [Line Items]
Estimated useful life	4 years