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Loans and Leases (Aging Of The Outstanding Loans and Leases By Class Excluding Loans Impaired At Acquisition Date) (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
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Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | $ 17,582,967fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities | $ 12,104,298fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities
Commercial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 11,263,074fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 8,499,348fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Construction and land development |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 550,568fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 319,847fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 7,552,948fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 6,362,490fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Other commercial real estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 244,875fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 178,754fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Commercial and industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 1,988,934fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 1,081,158fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Lease financing |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 571,916fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 381,763fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial | Other |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 353,833fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 175,336fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Noncommercial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 6,319,893fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember | 3,604,950fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember
Noncommercial | Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 2,520,542fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember | 982,421fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember
Noncommercial | Revolving mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 2,561,800fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember | 2,113,285fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember
Noncommercial | Construction and land development |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 120,097fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember | 122,792fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember
Noncommercial | Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans and leases, not acquired in a transfer accounted for as debt securities | 1,117,454fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember | 386,452fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember
Non-PCI Loans |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 57,321us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 44,167us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 19,548us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 14,236us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 24,598us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 30,828us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 101,467us-gaap_FinancingReceivableRecordedInvestmentPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 89,231us-gaap_FinancingReceivableRecordedInvestmentPastDue / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 17,481,500us-gaap_FinancingReceivableRecordedInvestmentCurrent / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 12,015,067us-gaap_FinancingReceivableRecordedInvestmentCurrent / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 17,582,967fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 12,104,298fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Construction and land development |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 1,796us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,603us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 621us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 9us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 385us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 457us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 2,802us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,069us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 547,766us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 317,778us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 550,568fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 319,847fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 11,367us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 11,131us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 4,782us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,601us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 8,061us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 14,407us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 24,210us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 29,139us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 7,528,738us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 6,333,351us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 7,552,948fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 6,362,490fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Other commercial real estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 206us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 139us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 70us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 210us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 102us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 470us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 378us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 819us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 244,497us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 177,935us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 244,875fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 178,754fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Commercial and industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 2,843us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,336us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 1,545us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 682us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 378us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 436us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 4,766us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 4,454us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 1,984,168us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,076,704us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 1,988,934fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,081,158fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Lease financing |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 1,631us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 789us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 8us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,341us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 2us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 101us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 1,641us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,231us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 570,275us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 379,532us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 571,916fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 381,763fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Commercial | Other |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 146us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 0us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 1,966us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 85us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 0us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 2,112us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 85us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 351,721us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 175,251us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 353,833fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 175,336fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Noncommercial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 39,332us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 27,169us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 10,556us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 8,308us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 15,670us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 14,957us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 6,254,335us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,554,516us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 6,319,893fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,604,950fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Noncommercial | Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 23,288us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 12,885us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 6,018us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 4,658us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 8,955us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 9,578us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 38,261us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 27,121us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 2,482,281us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 955,300us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 2,520,542fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 982,421fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Noncommercial | Revolving mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 11,097us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 10,977us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 2,433us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,378us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 5,463us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 4,450us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 18,993us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 17,805us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 2,542,807us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,095,480us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 2,561,800fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,113,285fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Noncommercial | Construction and land development |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 370us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,193us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 486us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 317us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 147us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 256us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 1,003us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,766us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 119,094us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 121,026us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | 120,097fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 122,792fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Non-PCI Loans | Noncommercial | Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
30-59 Days Past Due | 4,577us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,114us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
60-89 Days Past Due | 1,619us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 955us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
90 Days or Greater | 1,105us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 673us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Total | 7,301us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,742us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Current | 1,110,153us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 382,710us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Loans and leases, not acquired in a transfer accounted for as debt securities | $ 1,117,454fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | $ 386,452fcnca_Loansandleasesnotacquiredinatransferaccountedforasdebtsecurities / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember

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