XML 45 R53.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) (USD $) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | $ 2,092,936,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance | $ 1,727,492,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance |
Allowance for loan and lease losses | 205,553,000 us-gaap_LoansAndLeasesReceivableAllowance |  | 204,466,000 us-gaap_LoansAndLeasesReceivableAllowance
Non-PCI Loans |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 126,823,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 133,466,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 14,686,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 15,717,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 118,078,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 119,593,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 121,995,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 131,647,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 1,093,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,513,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Commercial | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 4,228,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 6,945,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 182,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 92,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 2,972,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,620,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 3,052,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,031,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 35,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 15,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Commercial | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 81,826,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 87,702,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 7,494,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 8,610,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 77,291,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 82,803,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 80,553,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 94,547,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 769,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,120,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / 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, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 847,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 913,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 104,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 112,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 543,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 584,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 551,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,796,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 1,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 21,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / 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, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 14,939,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 12,197,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 2,809,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,743,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 13,969,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 11,040,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 14,229,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 10,234,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 103,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 118,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Commercial | Lease financing |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 1,492,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 623,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 236,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 150,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 1,492,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 623,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 1,590,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 284,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 18,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 4,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Commercial | Other |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 1,977,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 2,000,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 1,955,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,972,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 1,977,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 2,000,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 1,990,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 0 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Noncommerical | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 15,852,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 15,746,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 1,177,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,360,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 15,195,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 14,913,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 15,364,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 16,482,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 125,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 174,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Noncommerical | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 733,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,340,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 90,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 71,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 733,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,340,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 658,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 2,322,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 7,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 29,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Noncommerical | Revolving mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 3,925,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 4,933,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 108,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,052,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 2,922,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 3,675,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 2,986,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 3,892,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 16,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 27,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | Noncommerical | Consumer |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Unpaid principal balance | 1,004,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 1,067,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
ALLL for loans and leases individually evaluated for impairment | 531,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 555,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Financing Receivable, Individually Evaluated for Impairment | 984,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |  | 995,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember
Average balance | 1,022,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 1,059,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Interest income recognized | 19,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember | 5,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember |
Non-PCI Loans | With A Recorded Allowance |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 83,497,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 87,007,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 2,114,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 996,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 53,220,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 57,324,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Other commercial real estate |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 104,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 112,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Commercial and industrial |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 13,123,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 10,319,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Lease financing |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 1,221,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 319,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Commercial | Other |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 1,977,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 2,000,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 8,662,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 10,198,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 733,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 1,077,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Revolving mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 1,439,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 3,675,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Consumer |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 904,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember |  | 987,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 34,581,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 32,586,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 858,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 624,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 24,071,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 25,479,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Other commercial real estate |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 439,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 472,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Commercial and industrial |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 846,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 721,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_CommercialAndIndustrialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Lease financing |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 271,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 304,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_FinanceLeasesFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Commercial | Other |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_OtherLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 6,533,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 4,715,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_MortgageReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Construction and land development |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 263,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = fcnca_ConstructionAndLandDevelopmentNoncommercialMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Revolving mortgage |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 1,483,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_HomeEquityMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Consumer |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Financing Receivable, Individually Evaluated for Impairment | 80,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember |  | 8,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = fcnca_NoncommercialSegmentMember / fcnca_LoanDesignationAxis = fcnca_NonPCILoansMember / us-gaap_ValuationAllowancesAndReservesTypeAxis = fcnca_WithNoRecordedAllowanceMember
PCI Loans |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |
Acquired loans which have adverse change in expected cash flows | $ 438,200,000 fcnca_AcquiredLoansWhichHaveAdverseChangeInExpectedCashFlows / fcnca_LoanDesignationAxis = fcnca_LoansAcquiredWithDeterioratedCreditQualityMember |  | $ 285,600,000 fcnca_AcquiredLoansWhichHaveAdverseChangeInExpectedCashFlows / fcnca_LoanDesignationAxis = fcnca_LoansAcquiredWithDeterioratedCreditQualityMember

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