Securities - Investments Pledged as Collateral to Secure Public Deposits and Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment and MBS pledged as collateral to secure public deposits and securities sold under agreements to repurchase	$ 164.8	$ 155.6
Mortgage-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment and MBS pledged as collateral to secure public deposits and securities sold under agreements to repurchase	93.2
Mortgage-Backed Securities | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment and MBS pledged as collateral to secure public deposits and securities sold under agreements to repurchase		95.4
Collateralized Mortgage Obligations
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment and MBS pledged as collateral to secure public deposits and securities sold under agreements to repurchase	30.1	18.8
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment and MBS pledged as collateral to secure public deposits and securities sold under agreements to repurchase	$ 41.5	$ 41.4