SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Jan. 01, 2021 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Summary Of Accounting Policies [Line Items]
Non-accrual debt securities	$ 0
Accrued interest related to debt securities	$ 0
Reasonable and supportable forecast, period	2 years
Income Taxes
Unrecognized Tax Benefits	$ 0			$ 0
Dividend Restriction
Period from which net retained earnings are available for dividend payment from the Bank to the Parent Company	2 years
Cash dividends paid to the Company	$ 26,500
Segment Reporting
Number of reportable operating segment | segment	1
Standards Effective in 2020
Allowance for credit losses	$ 44,200			32,786	$ 31,418	$ 31,707
Retained earnings	172,075			$ 150,703
Forecast
Dividend Restriction
Dividends from Bank to the Company, available amount		$ 49,800
ASU 2016-13 | Effect of adoption
Standards Effective in 2020
Allowance for credit losses	1,625		$ 1,600
Reserve for unfunded commitments			500
Retained earnings	$ 1,500		$ 0
Core deposit intangibles
Summary Of Accounting Policies [Line Items]
Core deposit intangible assets, useful life (in years)	10 years
Buildings
Summary Of Accounting Policies [Line Items]
Useful life	50 years
Equipment, computer hardware and software and furniture and fixtures | Minimum
Summary Of Accounting Policies [Line Items]
Useful life	2 years
Equipment, computer hardware and software and furniture and fixtures | Maximum
Summary Of Accounting Policies [Line Items]
Useful life	10 years