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Accounting Policies and Basis of Presentation Accounting Policies and Basis of Presentation (Recently Adopted Accounting Standards) (Details) (USD $) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2012 | Mar. 31, 2015 | Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Qualified Affordable Housing Projects Investments |  | $ 65,300,000 fcnca_QualifiedAffordableHousingProjectsInvestments | $ 57,100,000 fcnca_QualifiedAffordableHousingProjectsInvestments
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | $ 2,400,000 us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification |  |

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- Definition Investment balance in qualified affordable housing projects. + References No definition available. + Details
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- Definition Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements. + References No definition available. + Details
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- Details
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