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Securities - Additional Information (Details)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2024 USD ($) Security	Jun. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Segment Security	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Security
Schedule Of Held To Maturity Securities [Line Items]
Number of Investment Securities Segments | Segment				2
Credit losses				$ 0
Municipal securities percentage of securities portfolio	0.80%			0.80%
Securities in Unrealized Loss Positions Qualitative Disclosure Number of Positions Greater Than or Equal to One Year | Security	968			968		941
Gain (loss) on sale of investment securities	$ 0		$ 0	$ (9,400,000)	$ 0
Available for Sale Securities, Amortized Cost Basis	332,484,000			332,484,000		$ 440,358,000
Debt Securities, Available-for-Sale	331,414,000			331,414,000		438,588,000
Collateralized Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Available for Sale Securities, Amortized Cost Basis	10,280,000,000			10,280,000,000		11,340,000,000
Debt Securities, Available-for-Sale	$ 9,310,000,000			$ 9,310,000,000		$ 10,090,000,000.00
Securities Concentration Risk [Member] | Stockholders' Equity, Total [Member] | Other Than U.S. Government and Agencies [Member]
Schedule Of Held To Maturity Securities [Line Items]
Concentration Risk, Percentage				10.00%		10.00%
Visa Stock Exchange [Member]
Schedule Of Held To Maturity Securities [Line Items]
Conversion of stock, description				During the second quarter of 2024, the Bank tendered all of its shares of Visa, Inc. (“Visa”) Class B-1 common stock in exchange for a combination of Visa Class B-2 common stock and Visa Class C common stock, pursuant to the terms and subject to the conditions of the public offering of Visa to exchange its Class B-1 common stock for a combination of shares of its Class B-2 common stock and Class C common stock, which expired on May 3, 2024.
Gain on stock exchange		$ 20,600,000
Visa Stock Exchange [Member] | Class B-2 Common Stock [Member]
Schedule Of Held To Maturity Securities [Line Items]
Conversion of stock, shares converted | shares		48,492
Cost basis		$ 0
Visa Stock Exchange [Member] | Class C Common Stock [Member]
Schedule Of Held To Maturity Securities [Line Items]
Conversion of stock, shares converted | shares		19,245

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