Securities, Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Jun. 30, 2020
Available-for-sale Debt Securities, Amortized Cost [Abstract]
Within one year	$ 206,936
After one year through five years	6,160
After five years through ten years	30,832
After ten years	1,500
Total available-for-sale debt securities	245,428
Mortgage-backed securities	161,917
Amortized cost	407,345
Available-for-sale Debt Securities, Fair Value [Abstract]
Within one year	207,302
After one year through five years	6,271
After five years through ten years	30,316
After ten years	1,518
Total available-for-sale debt securities	245,407
Mortgage-backed securities	158,779
Estimated fair value	404,186	$ 226,709
Held-to-maturity Debt Securities, Amortized Cost [Abstract]
Within one year	44,456
After one year through five years	110,214
After five years through ten years	75,884
After ten years	77,163
Total held-to-maturity debt securities	307,717
Mortgage-backed securities	136,356
Amortized cost	444,073	383,657
Held-to-maturity Debt Securities, Fair Value [Abstract]
Within one year	45,152
After one year through five years	114,874
After five years through ten years	81,133
After ten years	82,140
Total held-to-maturity debt securities	323,299
Mortgage-backed securities	141,120
Estimated fair value	464,419	405,512
Total Debt Securities [Abstract]
Amortized cost	851,418	607,997
Estimated fair value	868,605	632,221
Securities pledged as collateral for deposits in excess of FDIC insurance limits, fair value	852,600	619,300
Securities pledged as collateral for potential borrowings at the Federal Reserve Bank discount window	$ 3,100	$ 4,700