Borrowings and Subordinated Debentures (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Other Borrowings, Fair Value Disclosure	$ 113,634,000	$ 118,838,000
Subordinated debt	952,740,000	941,923,000
Federal Reserve Bank Advances [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0	0
Federal Home Loan Bank of San Francisco
Debt Instrument [Line Items]
Collateralized Financings	10,300,000,000
Securities Loaned, Fair Value of Collateral	20,500,000
Letters of Credit Outstanding, Amount	(514,100,000)	(527,900,000)
Secured Debt | Federal Reserve Bank Advances [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	5,000,000,000.0
Collateralized Financings	4,600,000,000
Securities Loaned, Fair Value of Collateral	1,500,000,000
Secured Debt | Federal Home Loan Bank of San Francisco
Debt Instrument [Line Items]
Line of Credit Facility, Borrowing Capacity, Description	6,900,000,000
Line of Credit, Current	1,710,185,000	1,100,000,000
Unsecured Debt | 522110 Commercial Banking
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	0
Line of Credit Facility, Current Borrowing Capacity	$ 100,000,000.0
Debt Instrument, Basis Spread on Variable Rate	2.25%
Unused lines of Credit
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 215,000,000.0
Debt Instrument, Unused Borrowing Capacity, Fee	0
American Financial Exchange
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	240,000,000.0	0
Credit-Link Notes
Debt Instrument [Line Items]
Secured Debt	2,200,000,000
Other Borrowings, Fair Value Disclosure	$ 113,634,000	$ 118,838,000	$ 123,116,000	$ 132,030,000
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	14.63%	15.29%
Long-Term Debt, Weighted Average Interest Rate, at Point in Time	10.76%
Credit-Link Notes | Highest Rate of Spread
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	13.25%
Credit-Link Notes | Lowest Rate of Spread
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	8.00%