LOANS RECEIVABLE AND THE ALLOWANCE FOR CREDIT LOSSES (Loans by Type) (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	100.00%	100.00%
Unearned loan fees in excess of unamortized costs	$ 16,300	$ 16,500
Discount on acquired loans, net	2,100	2,400
Financing Receivable, Accrued Interest, before Allowance for Credit Loss	51,500	48,200
Financing Receivable, Loans Held as Collateral, FHLB and Other Borrowings	8,400,000	8,200,000
Financing Receivable, before Allowance for Credit Loss	11,707,626	11,721,687
Financing Receivable, after Allowance for Credit Loss	$ 11,547,274	$ 11,561,411
Commerical real estate - owner-occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	10.00%	10.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,176,035	$ 1,138,298
Commercial real estate - investment properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	15.00%	15.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,719,220	$ 1,701,413
Small balance CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	10.00%	10.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,218,388	$ 1,212,357
Multifamily Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	7.00%	7.00%
Financing Receivable, before Allowance for Credit Loss	$ 798,230	$ 850,789
Commercial construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	2.00%	1.00%
Financing Receivable, before Allowance for Credit Loss	$ 174,761	$ 156,021
Multifamily construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	4.00%	5.00%
Financing Receivable, before Allowance for Credit Loss	$ 502,166	$ 514,330
One- to four- family construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	5.00%	5.00%
Financing Receivable, before Allowance for Credit Loss	$ 617,233	$ 607,447
Land and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	3.00%	4.00%
Financing Receivable, before Allowance for Credit Loss	$ 400,959	$ 433,678
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	11.00%	11.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,231,154	$ 1,225,108
Small business scored
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	10.00%	10.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,199,913	$ 1,187,360
Agricultural business, including secured by farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	3.00%	3.00%
Financing Receivable, before Allowance for Credit Loss	$ 332,440	$ 353,152
One- to four-family residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	13.00%	13.00%
Financing Receivable, before Allowance for Credit Loss	$ 1,563,088	$ 1,573,191
Consumer—home equity revolving lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	6.00%	5.00%
Financing Receivable, before Allowance for Credit Loss	$ 682,692	$ 679,489
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of total loans	1.00%	1.00%
Financing Receivable, before Allowance for Credit Loss	$ 91,347	$ 89,054

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