LOANS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSSES - LOANS - Aging Analysis of Past Due Loans (Details)	Jun. 30, 2022 USD ($) loan	Dec. 31, 2021 USD ($) loan	Jun. 30, 2021 USD ($) loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	$ 1,971,039,000	$ 1,754,175,000	$ 1,672,898,000
Non-Accrual	$ 6,658,000
Number of TDR loans	0	0
Number of TDRs which incurred payment default | loan	0		0
REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	$ 1,248,513,000	$ 1,090,303,000	$ 981,463,000
Non-Accrual	950,000
CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	485,327,000	422,043,000	396,454,000
Non-Accrual	649,000
COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	237,199,000	241,829,000	$ 294,981,000
Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	299,181,000	264,429,000
Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	304,387,000	240,553,000
Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	49,292,000	41,017,000
Non-Accrual	151,000
One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	390,791,000	366,146,000
Non-Accrual	799,000
Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	204,862,000	178,158,000
Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	396,459,000	336,285,000
Non-Accrual	558,000
Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	85,806,000	82,778,000
Non-Accrual	91,000
Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	3,062,000	2,980,000
Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	203,331,000	208,552,000
Non-Accrual	5,059,000
Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	33,868,000	33,277,000
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	860,000	2,561,000
30-59 Days Past Due | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	6,000	593,000
30-59 Days Past Due | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	854,000	1,177,000
30-59 Days Past Due | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	791,000
30-59 Days Past Due | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
30-59 Days Past Due | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
30-59 Days Past Due | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	6,000	0
30-59 Days Past Due | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	593,000
30-59 Days Past Due | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
30-59 Days Past Due | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	787,000	1,047,000
30-59 Days Past Due | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	48,000	119,000
30-59 Days Past Due | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	19,000	11,000
30-59 Days Past Due | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	791,000
30-59 Days Past Due | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	484,000	546,000
60-89 Days Past Due | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	32,000	264,000
60-89 Days Past Due | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	452,000	282,000
60-89 Days Past Due | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	32,000	0
60-89 Days Past Due | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	264,000
60-89 Days Past Due | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	439,000	280,000
60-89 Days Past Due | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	13,000	2,000
60-89 Days Past Due | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
60-89 Days Past Due | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	$ 1,821,000	$ 972,000
Number Of Loans Accruing Interest | loan	0	0
90 Days or More Past Due | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	$ 482,000	$ 659,000
90 Days or More Past Due | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	252,000	313,000
90 Days or More Past Due | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,087,000	0
90 Days or More Past Due | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
90 Days or More Past Due | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
90 Days or More Past Due | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	151,000	179,000
90 Days or More Past Due | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	331,000	480,000
90 Days or More Past Due | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
90 Days or More Past Due | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	218,000	295,000
90 Days or More Past Due | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	34,000	0
90 Days or More Past Due | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	18,000
90 Days or More Past Due | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,087,000	0
90 Days or More Past Due | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	3,165,000	4,079,000
Past Due | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	520,000	1,516,000
Past Due | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,558,000	1,772,000
Past Due | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,087,000	791,000
Past Due | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
Past Due | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
Past Due | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	189,000	179,000
Past Due | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	331,000	1,337,000
Past Due | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
Past Due | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,444,000	1,622,000
Past Due | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	82,000	119,000
Past Due | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	32,000	31,000
Past Due | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,087,000	791,000
Past Due | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	0	0
Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,967,874,000	1,750,096,000
Not Past Due | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	1,247,993,000	1,088,787,000
Not Past Due | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	483,769,000	420,271,000
Not Past Due | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	236,112,000	241,038,000
Not Past Due | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	299,181,000	264,429,000
Not Past Due | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	304,387,000	240,553,000
Not Past Due | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	49,103,000	40,838,000
Not Past Due | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	390,460,000	364,809,000
Not Past Due | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	204,862,000	178,158,000
Not Past Due | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	395,015,000	334,663,000
Not Past Due | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	85,724,000	82,659,000
Not Past Due | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	3,030,000	2,949,000
Not Past Due | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	202,244,000	207,761,000
Not Past Due | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	33,868,000	33,277,000
Non-Accrual
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	6,658,000	5,829,000
Non-Accrual | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	950,000	781,000
Non-Accrual | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	649,000	629,000
Non-Accrual | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	5,059,000	4,419,000
Non-Accrual | Commercial | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	0	0
Non-Accrual | Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	0	0
Non-Accrual | Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	151,000	301,000
Non-Accrual | One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	799,000	480,000
Non-Accrual | Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	0	0
Non-Accrual | Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	558,000	554,000
Non-Accrual | Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	91,000	57,000
Non-Accrual | Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	0	18,000
Non-Accrual | Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	5,059,000	4,419,000
Non-Accrual | Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Accrual	$ 0	$ 0