Loans and Allowance for Credit Losses - Purchased participation and loans with modifications (Details) $ in Millions	9 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of purchased participation loans	22	23
Purchased participation loans	$ 75.3	$ 58.2
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount of Loans Modified for Other Than TDR	$ 28.0	$ 48.8
Number of Loans Modified for Other Than TDR	52	77