Borrowings and Subordinated Debentures (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	4.92%	5.36%
Borrowings	$ 2,915,416	$ 1,764,030
Acquisition Discount on Senior Notes	(4,094)	0
Long-Term Debt	2,911,322	1,764,030
Other Borrowings, Fair Value Disclosure	$ 123,116	$ 132,030
Credit-Link Notes
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	16.02%	14.56%
Long-term Debt, Percentage Bearing Variable Interest, Amount	$ 132,800	$ 132,030
Other Borrowings, Fair Value Disclosure	$ 123,116	$ 132,030	$ 0
American Financial Exchange
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	0.00%	4.68%
Line of Credit Facility, Amount Outstanding	$ 0	$ 250,000
Five Point Two Five Percent Senior Notes Due April152025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.25%	0.00%
Senior Notes	$ 174,000	$ 0
Federal Home Loan Bank of San Francisco \| Secured Debt
Debt Instrument [Line Items]
Line of Credit, Current	$ 0	$ 1,270,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	0.00%	4.62%
Federal Home Loan Bank of San Francisco \| Secured Debt \| Bank Term Funding Program
Debt Instrument [Line Items]
Line of Credit, Current	$ 2,618,300	$ 0
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	4.37%	0.00%
Federal Home Loan Bank of San Francisco \| Unsecured Debt
Debt Instrument [Line Items]
Line of Credit, Current	$ 0	$ 112,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	0.00%	4.37%

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- Definition

Other Borrowings, Fair Value Disclosure

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- Definition

Total Borrowings

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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