FAIR VALUE - Summary of assets measured at fair value on recurring basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	$ 32,233	$ 36,666
Mortgage loans held for sale	51,309	161,843
U.S. Treasury debt
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	249	254
Corporate bonds
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	8,356	6,044
Recurring
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	32,233	36,666
Equity securities	716	730
Guarantee asset	231	232
Mortgage loans held for sale	51,309	161,843
Recurring | U.S. Treasury debt
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	249	254
Recurring | Corporate bonds
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	8,356	6,044
Recurring | Corporate collateralized mortgage obligations and mortgage-backed securities
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	1,662	4,087
Recurring | IRLC,net
Summary of assets measured on a recurring and nonrecurring basis
Derivative asset, Fair value	2,185	9,841
Recurring | Forward Commitment
Summary of assets measured on a recurring and nonrecurring basis
Derivative asset, Fair value	481	(2,623)
Recurring | GNMA | mortgage-backed securities - residential
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	20,811	24,604
Recurring | FNMA | mortgage-backed securities - residential
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	1,155	1,677
Level 1 | Recurring
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	249	254
Equity securities	716	730
Level 1 | Recurring | U.S. Treasury debt
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	249	254
Level 2 | Recurring
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	31,984	36,412
Mortgage loans held for sale	51,309	161,843
Level 2 | Recurring | Corporate bonds
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	8,356	6,044
Level 2 | Recurring | Corporate collateralized mortgage obligations and mortgage-backed securities
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	1,662	4,087
Level 2 | Recurring | Forward Commitment
Summary of assets measured on a recurring and nonrecurring basis
Derivative asset, Fair value	498	(2,534)
Level 2 | Recurring | GNMA | mortgage-backed securities - residential
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	20,811	24,604
Level 2 | Recurring | FNMA | mortgage-backed securities - residential
Summary of assets measured on a recurring and nonrecurring basis
Available-for-sale securities, at fair value	1,155	1,677
Level 3 | Recurring
Summary of assets measured on a recurring and nonrecurring basis
Guarantee asset	231	232
Level 3 | Recurring | IRLC,net
Summary of assets measured on a recurring and nonrecurring basis
Derivative asset, Fair value	2,185	9,841
Level 3 | Recurring | Forward Commitment
Summary of assets measured on a recurring and nonrecurring basis
Derivative asset, Fair value	$ (17)	$ (89)