Fair Value of Financial Instruments - Carrying value and fair value of financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Financial assets:
Loans receivable, net	$ 494,805	$ 508,605
Financial liabilities:
Certificates of deposit	194,148	194,480
Advances from Federal Home Loan Bank	41,000	64,892
Level 3
Financial assets:
Loans receivable, net	517,970	541,779
Financial liabilities:
Certificates of deposit	196,632	198,268
Advances from Federal Home Loan Bank	42,269	67,520
Carrying Value
Financial assets:
Loans receivable, net	494,805	508,605
Financial liabilities:
Certificates of deposit	194,148	194,480
Advances from Federal Home Loan Bank	41,000	64,892
Fair Value
Financial assets:
Loans receivable, net	517,970	541,779
Financial liabilities:
Certificates of deposit	196,632	198,268
Advances from Federal Home Loan Bank	$ 42,269	$ 67,520