FEDERAL HOME LOAN BANK ADVANCES AND OTHER BORROWINGS - Additional Information (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Advances from FHLB collateralized	$ 2,970,000,000	$ 3,050,000,000.00
Securities sold under repurchase agreements	0	0
Line of Credit \| Unsecured Federal Funds Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility	185,000,000.0
Other borrowings	0
Federal Reserve Bank Advances
Line of Credit Facility [Line Items]
Line of credit facility	15,900,000
Other borrowings	0
Collateralized loan obligations \| Federal Reserve Bank Advances
Line of Credit Facility [Line Items]
Collateral on line of credit facility	22,500,000
Federal Home Loan Bank of San Francisco
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
FHLB stock	30,100,000	$ 32,300,000
Amount of additional available borrowing	$ 921,400,000

Amount of assets pledged to secure a debt instrument.

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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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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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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