XML 69 R58.htm IDEA: XBRL DOCUMENT
v3.21.2

Mortgage Servicing Rights (Narrative) (Details) - USD ($) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Mortgage Servicing Rights [Abstract] |  |  |  |  |
Residential Mortgage Loans Serviced | $ 3,300,000,000 |  | $ 3,300,000,000 |  | $ 3,300,000,000
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset | 2,100,000 | $ 2,100,000 | 6,400,000 | $ 6,400,000 |
Valuation allowance increase | $ 0 | $ 305,000 | $ (1,339,000) | $ 4,341,000 |

X
- Definition Mortgage Servicing Rights [Abstract] + References No definition available. + Details
Name: | fcnca_MortgageServicingRightsAbstract
Namespace Prefix: | fcnca_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Unpaid principal balance of residential mortgage loans serviced for others at period end. + References No definition available. + Details
Name: | fcnca_ResidentialMortgageLoansServiced
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of contractually specified servicing fee, late fee, and ancillary fee recognized as income for servicing asset and servicing liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746 + Details
Name: | us-gaap_ContractuallySpecifiedServicingFeesLateFeesAndAncillaryFeesEarnedInExchangeForServicingFinancialAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from expenses (recoveries) recognized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 4 -Subparagraph (e)(2) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746 + Details
Name: | us-gaap_ValuationAllowanceForImpairmentOfRecognizedServicingAssetsProvisionsRecoveries
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration