XML 169 R150.htm IDEA: XBRL DOCUMENT v3.25.4

COMMITMENTS AND CONTINGENCIES - Schedule of Fair Value, Off-balance Sheet Risks (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Financing assets (excluding leases)
Other Commitments [Line Items]
Credit related commitments	$ 51,726	$ 53,250
Financial standby letters of credit
Other Commitments [Line Items]
Credit related commitments	2,583	2,188
Other letters of credit
Other Commitments [Line Items]
Credit related commitments	227	103
Deferred Purchase Agreements
Other Commitments [Line Items]
Credit related commitments	1,723	1,802
Purchase and Funding Commitments
Other Commitments [Line Items]
Credit related commitments	$ 102	$ 178

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

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=us-gaap_UnfundedLoanCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=fcnca_OtherLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=fcnca_DeferredPurchaseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=fcnca_LessorCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: