Loans and Allowance for Credit Losses - Non-TDR Loan Modifications due to COVID-19 (Details) - CARES Act Modification $ in Thousands	3 Months Ended
	Dec. 31, 2020 USD ($) numberOfLoanPortfolios
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount [Roll Forward]
June 30, 2020 Deferrals Balance	$ 137,572
Booked Amount End of Period Balance	$ 63,902
December 31, 2020 Number of Deferrals | numberOfLoanPortfolios	455
Commercial and commercial real estate
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount [Roll Forward]
June 30, 2020 Deferrals Balance	$ 125,603
Booked Amount End of Period Balance	$ 53,823
December 31, 2020 Number of Deferrals | numberOfLoanPortfolios	101
Second deferrals between 90 and 180 days, amount	$ 6,300
Residential real estate
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount [Roll Forward]
June 30, 2020 Deferrals Balance	1,654
Booked Amount End of Period Balance	$ 1,855
December 31, 2020 Number of Deferrals | numberOfLoanPortfolios	6
Consumer
Financing Receivable, Non-Troubled Debt Restructuring Modifications, Amount [Roll Forward]
June 30, 2020 Deferrals Balance	$ 10,315
Booked Amount End of Period Balance	$ 8,224
December 31, 2020 Number of Deferrals | numberOfLoanPortfolios	348
Second deferrals between 90 and 180 days, amount	$ 600