DISCLOSURES ABOUT FAIR VALUE OF FINANCIAL INSTRUMENTS - Schedule Of Financial Instruments Fair Value (Details) $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Junior Subordinated Debt
Financial Instruments Owned Carrying Amount	$ 25,774	$ 25,774
Financial Instruments, Owned, at Fair Value	$ 25,774	$ 25,774
Fair Value Hierarchy Level	3	3
Subordinated Debt
Financial Instruments Owned Carrying Amount	$ 148,580	$ 148,397
Financial Instruments, Owned, at Fair Value	$ 157,125	$ 157,032
Fair Value Hierarchy Level	2	2
Deposits
Financial Instruments Owned Carrying Amount	$ 4,626,936	$ 4,516,903
Financial Instruments, Owned, at Fair Value	$ 4,631,388	$ 4,523,586
Fair Value Hierarchy Level	3	3
Short-term Debt
Financial Instruments Owned Carrying Amount	$ 143,302	$ 165,692
Financial Instruments, Owned, at Fair Value	$ 143,302	$ 165,692
Fair Value Hierarchy Level	3	3
Unrecognized financial instruments (net of contractual value) | Commitments to Originate Loans
Fair Value Hierarchy Level	3	3
Unrecognized financial instruments (net of contractual value) | Letter of Credit
Financial Instruments Owned Carrying Amount	$ 68	$ 84
Financial Instruments, Owned, at Fair Value	$ 68	$ 84
Fair Value Hierarchy Level	3	3
Unrecognized financial instruments (net of contractual value) | Line of Credit
Fair Value Hierarchy Level	3	3
Interest payable
Financial Instruments Owned Carrying Amount	$ 2,444	$ 2,594
Financial Instruments, Owned, at Fair Value	$ 2,444	$ 2,594
Fair Value Hierarchy Level	3	3
Loans Receivable
Financial Instruments Owned Carrying Amount	$ 4,285,737	$ 4,296,804
Financial Instruments, Owned, at Fair Value	$ 4,297,186	$ 4,303,909
Fair Value Hierarchy Level	3	3
Cash and Cash Equivalents
Financial Instruments Owned Carrying Amount	$ 612,556	$ 563,729
Financial Instruments, Owned, at Fair Value	$ 612,556	$ 563,729
Fair Value Hierarchy Level	1	1
Mortgage loans held for sale
Financial Instruments Owned Carrying Amount	$ 30,492	$ 17,780
Financial Instruments, Owned, at Fair Value	$ 30,492	$ 17,780
Fair Value Hierarchy Level	2	2
Interest receivable
Financial Instruments Owned Carrying Amount	$ 13,027	$ 12,793
Financial Instruments, Owned, at Fair Value	$ 13,027	$ 12,793
Fair Value Hierarchy Level	3	3
Investment in FHLBank stock and other interest-earning assets
Financial Instruments Owned Carrying Amount	$ 6,655	$ 9,806
Financial Instruments, Owned, at Fair Value	$ 6,655	$ 9,806
Fair Value Hierarchy Level	3	3