BASIS OF PRESENTATION (Narrative) (Details) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 27, 2024 $ / shares	Jul. 31, 2024 USD ($) bank	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2024 USD ($) segment $ / shares	Apr. 28, 2024 $ / shares shares	Feb. 28, 2024 bank	Dec. 31, 2023 USD ($) $ / shares
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares				$ 1	$ 1			$ 1
Number of operating segments | segment					1
Qualified Affordable Housing Investments
Affordable housing project investments				$ 5,500	$ 5,500			$ 5,900
Affordable housing tax credits, amount				257	513
Affordable housing, other tax benefits, amount				33	66
Affordable housing tax credits and other tax benefits, amount				290	579
Affordable housing project investments, amortization				235	470
Income (loss) from affordable housing projects				$ 55	$ 109
Rocky Mountain Bank
Business Acquisition [Line Items]
Disposal group, number of bank branches | bank							9
Rocky Mountain Bank | Forecast
Business Acquisition [Line Items]
Proceeds from Sale of Loans Receivable			$ 30,000
Subsequent Event | Rocky Mountain Bank
Business Acquisition [Line Items]
Disposal group, number of bank branches | bank		9
Time Deposits, Sold		$ 531,800
Financing Receivable, Sale		$ 343,800
Bank Merger
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares						$ 1.00
Business combination, equity interest conversion per common share (in shares) | shares						0.55
Business combination, equity interest conversion, per preferred share (in shares) | shares						1
Bank Merger | HTLF
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 1.00
Preferred stock, percentage	7.00%
Preferred stock, par value (in dollars per share) | $ / shares	$ 1.00