XML 111 R95.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Employee Benefit Plans (Fair Value and Allocation Of Plan Assets) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 600,616 | $ 550,025 | $ 544,956
Actual % of Plan Assets | 100.00% | 100.00% |
BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 517,858 | $ 469,647 |
BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 82,758 | 80,378 |
BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 152,084 | 150,893 | $ 155,618
Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 124,940 | 126,392 |
Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 27,144 | 24,501 |
Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Cash and equivalents | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 60,674 | $ 26,613 |
Actual % of Plan Assets | 10.00% | 5.00% |
Cash and equivalents | BancShares Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
Cash and equivalents | BancShares Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 1.00% | 1.00% |
Cash and equivalents | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 60,674 | $ 26,613 |
Cash and equivalents | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Cash and equivalents | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Cash and equivalents | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 3,839 | $ 13,437 |
Actual % of Plan Assets | 2.49% | 8.90% |
Cash and equivalents | Bancorporation Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% |  |
Cash and equivalents | Bancorporation Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 1.00% |  |
Cash and equivalents | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 3,839 | $ 13,437 |
Cash and equivalents | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Cash and equivalents | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Equity Securities | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 66,015 | $ 267,037 |
Actual % of Plan Assets | 54.00% | 63.00% |
Equity Securities | BancShares Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 55.00% |
Equity Securities | BancShares Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 70.00% | 65.00% |
Equity Securities | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 65,964 | $ 267,037 |
Equity Securities | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 51 | 0 |
Equity Securities | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Equity Securities | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 18,274 | $ 80,676 |
Target Allocation | 60.00% |  |
Actual % of Plan Assets | 58.00% | 63.00% |
Equity Securities | Bancorporation Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% |  |
Equity Securities | Bancorporation Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 70.00% |  |
Equity Securities | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 18,260 | $ 80,676 |
Equity Securities | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 14 | 0 |
Equity Securities | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 0 | $ 0 |
Debt Securities | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Actual % of Plan Assets | 28.00% | 26.00% |
Debt Securities | BancShares Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 15.00% | 25.00% |
Debt Securities | BancShares Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 45.00% | 40.00% |
Debt Securities | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Actual % of Plan Assets | 31.00% | 22.00% |
Debt Securities | Bancorporation Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 15.00% |  |
Debt Securities | Bancorporation Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 45.00% |  |
Equity mutual funds | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 256,976 | $ 78,645 |
Equity mutual funds | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 252,710 | 78,645 |
Equity mutual funds | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 4,266 | 0 |
Equity mutual funds | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Equity mutual funds | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 69,978 | 15,005 |
Equity mutual funds | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 68,832 | 15,005 |
Equity mutual funds | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 1,146 | 0 |
Equity mutual funds | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
US government and government agency securities | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 57,890 | 58,526 |
US government and government agency securities | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 47,647 | 48,957 |
US government and government agency securities | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 10,243 | 9,569 |
US government and government agency securities | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
US government and government agency securities | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 15,407 | 20,476 |
US government and government agency securities | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 8,919 | 3,986 |
US government and government agency securities | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 6,488 | 16,490 |
US government and government agency securities | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Corporate Bonds | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 68,198 | 70,809 |
Corporate Bonds | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Corporate Bonds | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 68,198 | 70,809 |
Corporate Bonds | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Corporate Bonds | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 19,496 | 8,011 |
Corporate Bonds | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Corporate Bonds | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 19,496 | 8,011 |
Corporate Bonds | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Fixed Income Mutual Funds | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 42,849 | 17,351 |
Fixed Income Mutual Funds | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 42,849 | 17,351 |
Fixed Income Mutual Funds | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Fixed Income Mutual Funds | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Fixed Income Mutual Funds | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 11,822 | 4,198 |
Fixed Income Mutual Funds | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 11,822 | 4,198 |
Fixed Income Mutual Funds | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Fixed Income Mutual Funds | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Alternative investments | BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 48,014 | $ 31,044 |
Actual % of Plan Assets | 8.00% | 6.00% |
Alternative investments | BancShares Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
Alternative investments | BancShares Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 8.00% |
Alternative investments | BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 48,014 | $ 31,044 |
Alternative investments | BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Alternative investments | BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Alternative investments | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 13,268 | 9,090 |
Actual % of Plan Assets | 9.00% |  |
Defined Benefit Plan, Target Allocation Percentage | 0.05 |  |
Alternative investments | Bancorporation Plan | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% |  |
Alternative investments | Bancorporation Plan | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% |  |
Alternative investments | Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 13,268 | 9,090 |
Alternative investments | Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Alternative investments | Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 0 | $ 0 |
Fixed Income And Cash | Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 35.00% |  |

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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6749337 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6520858 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Description of target allocation percentages, or range of percentages, considering the major categories of plan assets as of the latest statement of financial position presented (on a weighted-average basis for employers with more than one plan) that are pertinent to an understanding of the plan investment policies and strategies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanTargetAllocationPercentage
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Target allocation of investments of this type to total plan assets presented on a weighted average basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=fcnca_BancSharesPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=fcnca_BancorporationPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquityFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_FixedIncomeFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=fcnca_AlternativeinvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=fcnca_FixedIncomeAndCashMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |