Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($)	Mar. 31, 2020	Jun. 30, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Held-to-maturity Securities	$ 0
Accrued interest receivable for investment securities	7,100,000
Threshold Net Book Balance, Individually Evaluated Loans	250,000
Interest Receivable	30,200,000
Liability Recorded for Expected Credit Losses on Unfunded Commitments	$ 8,600,000
Other Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest Receivable		$ 30,200,000
Other Liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liability Recorded for Expected Credit Losses on Unfunded Commitments		$ 8,600,000