Derivatives (Schedule Of Interest Rate Swaps) (Details) - 2011 Interest Rate Swap - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Interest Rate Cash Flow Hedge Liability at Fair Value	$ 0	$ 1,429
Derivative, Notional Amount		$ 93,500

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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- 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

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- Definition

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=fcnca_InterestRateSwapHedgingVariableRateExposureOnTrustPreferredSecurities20112016Member
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