XML 80 R70.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Loans and Leases - Narrative (Details) - USD ($) $ in Millions | Jan. 03, 2022 | Sep. 30, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Receivables [Abstract] |  |  |
Financing receivable, accrued interest receivable |  | $ 171.0 | $ 87.0
Financing receivable, threshold period past due |  | 30 days |
Other real estate owned |  | $ 54.0 | 40.0
Financing receivable, troubled debt restructuring, commitment to lend |  | $ 3.0 | $ 0.4
CIT Group Inc. |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases | $ 32,714.0 |  |
CIT Group Inc. | Non-PCD |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Purchase accounting adjustment of discount | (61.0) |  |
CIT Group Inc. | Non-PCD | Commercial | Leases |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Loans and leases | $ 29,500.0 |  |

X
- Definition Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financing Receivable + References No definition available. + Details
Name: | fcnca_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinancingReceivable
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Financing Receivable, Purchased Without Credit Deterioration, Discount (Premium), Purchase Accounting Adjustments + References No definition available. + Details
Name: | fcnca_FinancingReceivablePurchasedWithoutCreditDeteriorationDiscountPremiumPurchaseAccountingAdjustments
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Amount, after allowance for credit loss, of accrued interest on financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3A -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL120267960-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=124255206&loc=SL120267845-210446 + Details
Name: | us-gaap_FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Threshold period for when financing receivable is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447 + Details
Name: | us-gaap_FinancingReceivableThresholdPeriodPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554 + Details
Name: | us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of other real estate and foreclosed assets. Other real estate may include real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10(4)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 + Details
Name: | us-gaap_OtherRealEstateAndForeclosedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ReceivablesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fcnca_CITGroupIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredAndNoCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcnca_FinancingReceivableLeasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |