XML 75 R65.htm IDEA: XBRL DOCUMENT
v3.22.2

Investment Securities - Schedule of Interest and Dividends on Investment Securities (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Investments [Abstract] |  |  |  |
Interest income - taxable investment securities | $ 89 | $ 36 | $ 171 | $ 65
Dividend income - marketable equity securities | 0 | 0 | 1 | 1
Interest on investment securities | $ 89 | $ 36 | $ 172 | $ 66

X
- Definition Interest Income, Investment Securities, Operating, Taxable + References No definition available. + Details
Name: | fcnca_InterestIncomeInvestmentSecuritiesOperatingTaxable
Namespace Prefix: | fcnca_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of dividend income on investment in equity security, classified as operating. + References No definition available. + Details
Name: | us-gaap_DividendIncomeEquitySecuritiesOperating
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.2) -URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1402 -Paragraph (a) Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1402 -Paragraph (b) -Subparagraph (1) + Details
Name: | us-gaap_InterestIncomeSecuritiesTaxable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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