Borrowed Funds - Components of Short-Term and Long-Term Debt (Parenthetical) (Detail)	Mar. 31, 2024	Dec. 31, 2023
Federal Home Loan Bank 5.04% and 5.04% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	5.04%	5.04%
Federal Reserve Bank Term Funding Program 4.76% and 4.83% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.76%	4.83%
Marquette Capital Trust I Subordinated Debentures 6.91% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	6.91%	6.91%
Marquette Capital Trust II Subordinated Debentures 6.91% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	6.91%	6.91%
Marquette Capital Trust III Subordinated Debentures 7.08% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.08%	7.08%
Marquette Capital Trust IV Subordinated Debentures 7.19% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.19%	7.19%
Subordinated notes 3.70%, net of issuance costs [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	3.70%	3.70%
Subordinated notes 6.25%, net issuance costs [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	6.25%	6.25%