Commitments and Contingencies - Commitment (Details) - Commitments to Extend Credit - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	$ 505,142	$ 312,272
REAL ESTATE LOANS.
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	373,626	183,477
Commercial
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	1,332	247
Construction and development
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	106,862	95,031
One-to-four-family
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	218,244	39,697
Home equity.
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	46,558	47,880
Commercial/Multi-family
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	630	622
CONSUMER LOANS.
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	22,331	22,176
COMMERCIAL BUSINESS LOANS.
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	109,185	106,619
Commercial and industrial
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	82,202	72,731
Warehouse lending
Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments	$ 26,983	$ 33,888