Loans Held for Investment - Schedule of restructured loan balances, net of allowance for loan losses, by loan type and by Nonaccrual Versus Accrual Status (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020
Financing Receivable, Modifications [Line Items]
Restructured loans on non-accrual status	$ 2,448	$ 2,643
Restructured loans	2,448	2,643
Mortgage loans, Single-family
Financing Receivable, Modifications [Line Items]
Restructured loans on non-accrual status	2,421	2,612
Commercial business loans
Financing Receivable, Modifications [Line Items]
Restructured loans on non-accrual status	$ 27	$ 31

Amount of financing receivable on nonaccrual status.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant