XML 132 R121.htm IDEA: XBRL DOCUMENT
v3.24.2.u1

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions | Jun. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Other Commitments [Line Items] |  |
Deferred purchase agreement, borrowings by client | $ 132 | $ 143
Deferred purchase agreement, receivables with credit risk | 1,380 | 1,920
Deferred purchase agreement, line of credit facility, maximum borrowing capacity | 49 | 161
Loss contingency (up to) | 10 |
Off-Balance Sheet Commitment |  |
Other Commitments [Line Items] |  |
Credit related commitments | $ 72 | $ 66

X
- Definition Credit Extension Commitments, Notional Amount + References No definition available. + Details
Name: | fcnca_CreditExtensionCommitmentsNotionalAmount
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Deferred Purchase Agreement Borrowings By Client + References No definition available. + Details
Name: | fcnca_DeferredPurchaseAgreementBorrowingsByClient
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Deferred Purchase Agreement, Line of Credit Facility, Maximum Borrowing Capacity + References No definition available. + Details
Name: | fcnca_DeferredPurchaseAgreementLineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Deferred Purchase Agreement, Receivables With Credit Risk + References No definition available. + Details
Name: | fcnca_DeferredPurchaseAgreementReceivablesWithCreditRisk
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-4 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-9 + Details
Name: | us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_OtherCommitmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fcnca_OffBalanceSheetCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |