Securities, Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Available-for-sale Debt Securities, Amortized Cost [Abstract]
Within one year	$ 193,109
After one year through five years	3,689
After five years through ten years	8,542
After ten years	1,500
Total available-for-sale debt securities	206,840
Mortgage-backed securities	123,163
Amortized cost	330,003
Available-for-sale Debt Securities, Fair Value [Abstract]
Within one year	193,670
After one year through five years	3,786
After five years through ten years	8,558
After ten years	1,511
Total available-for-sale debt securities	207,525
Mortgage-backed securities	124,579
Estimated fair value	332,104	$ 226,709
Held-to-maturity Debt Securities, Amortized Cost [Abstract]
Within one year	41,684
After one year through five years	102,444
After five years through ten years	69,549
After ten years	60,911
Total held-to-maturity debt securities	274,588
Mortgage-backed securities	134,181
Amortized cost	408,769	383,657
Held-to-maturity Debt Securities, Fair Value [Abstract]
Within one year	42,395
After one year through five years	107,389
After five years through ten years	75,648
After ten years	66,479
Total held-to-maturity debt securities	291,911
Mortgage-backed securities	142,018
Estimated fair value	433,929	405,512
Total Debt Securities [Abstract]
Amortized cost	738,772	607,997
Estimated fair value	766,033	632,221
Securities pledged as collateral for deposits in excess of FDIC insurance limits, fair value	719,800	619,300
Securities pledged as collateral for potential borrowings at the Federal Reserve Bank discount window	$ 4,200	$ 4,700