Borrowed Funds - Additional Information (Detail) - USD ($)	1 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2020	Sep. 30, 2023
Debt Instrument [Line Items]
Payments to acquire federal home loan bank stock			$ 70,200,000
Short-term borrowing outstanding			2,300,000,000
Federal Home Loan Bank 5.04% due 2024 [Member]
Debt Instrument [Line Items]
Short-term borrowing outstanding			1,000,000,000
Federal Home Loan Bank 5.47% due 2023 [ Member]
Debt Instrument [Line Items]
Short-term borrowing outstanding			500,000,000
Letter of Credit [Member] | Federal Home Loan Bank 5.04% due 2024 [Member]
Debt Instrument [Line Items]
Revolving line of credit outstanding amount			$ 150,000,000
Letter of credit, expiration date			Jan. 31, 2024
Borrowing capacity			$ 436,700,000
Wells Fargo Bank 1.40% due 2012 [Member]
Debt Instrument [Line Items]
Interest rate based on SOFR			1.40% above Term SOFR
Revolving line of credit outstanding amount			$ 0
Borrowing capacity			$ 30,000,000
Debt instrument, interest rate based on prime lending rate			1.75% below the prime
Revolving line of credit, commitment fee for unused portion			0.40%
Subordinated notes 3.70% due 2030, net of issuance costs [Member]
Debt Instrument [Line Items]
Debt instrument, issuance date		Sep. 30, 2020
Subordinated notes, issued		$ 200,000,000
Debt instrument, interest rate		3.70%
Debt instrument, maturity date		Sep. 17, 2030
Debt instrument, frequency of periodic payment			semi-annually
Debt instrument, redemption, description			The Company may redeem the notes, in whole or in part, on September 17, 2025, or on any interest payment date thereafter.
Unamortized debt issuance costs		$ 900,000
Subordinated notes 6.25% due 2032, net issuance costs [Member]
Debt Instrument [Line Items]
Debt instrument, issuance date	Sep. 30, 2022
Subordinated notes, issued	$ 110,000,000
Debt instrument, interest rate	6.25%
Debt instrument, maturity date	Sep. 28, 2032
Debt instrument, frequency of periodic payment			semi-annually
Debt instrument, redemption, description			The Company may redeem the notes, in whole or in part, on September 28, 2027, or on any interest payment date thereafter.
Unamortized debt issuance costs			$ 1,700,000
Marquette Capital Trust I, Marquette Capital Trust II, Marquette Capital Trust III And Marquette Capital Trust IV [Member] | Marquette [Member]
Debt Instrument [Line Items]
Long-term debt			103,100,000
Long-term debt acquired at fair value			$ 75,400,000
Trust Preferred Securities [Member] | Marquette Capital Trust I, Marquette Capital Trust II, Marquette Capital Trust III And Marquette Capital Trust IV [Member] | Marquette [Member]
Debt Instrument [Line Items]
Interest rate based on SOFR			Secured Overnight Financing Rate (SOFR) with spreads ranging from 133 basis points to 160 basis points
Preferred securities maturity date range, start			Jan. 31, 2036
Preferred securities maturity date range, end			Sep. 30, 2036
Federal Reserve Bank's Bank Term Funding Program [Member]
Debt Instrument [Line Items]
Short-term borrowing outstanding			$ 800,000,000
Borrowing capacity			20,000,000
Federal Reserve Discount Window 4.70% due 2023 [Member]
Debt Instrument [Line Items]
Borrowing capacity			$ 10,200,000,000
Minimum [Member] | Trust Preferred Securities [Member] | Marquette Capital Trust I, Marquette Capital Trust II, Marquette Capital Trust III And Marquette Capital Trust IV [Member] | Marquette [Member]
Debt Instrument [Line Items]
Interest rate of trust preferred securities			1.33%
Maximum [Member] | Trust Preferred Securities [Member] | Marquette Capital Trust I, Marquette Capital Trust II, Marquette Capital Trust III And Marquette Capital Trust IV [Member] | Marquette [Member]
Debt Instrument [Line Items]
Interest rate of trust preferred securities			1.60%