Securities, Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Available-for-sale Debt Securities, Amortized Cost [Abstract]
Within one year	$ 200,332
After one year through five years	5,676
After five years through ten years	28,687
After ten years	1,500
Total available-for-sale debt securities	236,195
Mortgage-backed and asset-backed securities	154,220
Amortized cost	390,415	$ 224,340
Available-for-sale Debt Securities, Fair Value [Abstract]
Within one year	200,547
After one year through five years	5,800
After five years through ten years	28,671
After ten years	1,484
Total available-for-sale debt securities	236,502
Mortgage-backed and asset-backed securities	154,388
Estimated fair value	390,890	226,709
Held-to-maturity Debt Securities, Amortized Cost [Abstract]
Within one year	43,549
After one year through five years	116,982
After five years through ten years	93,191
After ten years	114,412
Total held-to-maturity debt securities	368,134
Mortgage-backed securities	128,780
Amortized cost	496,914	383,657
Held-to-maturity Debt Securities, Fair Value [Abstract]
Within one year	44,346
After one year through five years	121,829
After five years through ten years	98,778
After ten years	120,192
Total held-to-maturity debt securities	385,145
Mortgage-backed securities	133,897
Estimated fair value	519,042	405,512
Total Debt Securities [Abstract]
Amortized cost	887,329	607,997
Estimated fair value	909,932	632,221
Securities pledged as collateral for deposits in excess of FDIC insurance limits, fair value	892,100	619,300
Securities pledged as collateral for potential borrowings at the Federal Reserve Bank discount window	$ 3,900	$ 4,700