Other Real Estate Owned (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
Covered
Beginning Balance	$ 47,081us-gaap_OtherRealEstateCovered	$ 102,577us-gaap_OtherRealEstateCovered	$ 22,982us-gaap_OtherRealEstateCovered
Additions	29,708us-gaap_OtherRealEstateCoveredAdditions	59,034us-gaap_OtherRealEstateCoveredAdditions
Sales	(38,753)us-gaap_OtherRealEstateCoveredDisposals	(96,744)us-gaap_OtherRealEstateCoveredDisposals
Writedowns	(10,853)	(17,786)
Other Real Estate Covered Transfers	(5,537)fcnca_OtherRealEstateCoveredTransfers
Noncovered
Beginning balance	36,898us-gaap_OtherRealEstateNonCovered	43,513us-gaap_OtherRealEstateNonCovered	70,454us-gaap_OtherRealEstateNonCovered
Additions	36,574	33,908
Sales	(48,935)	(36,168)
Writedowns	(5,219)	(4,355)
Other Real Estate Non Covered Transfers	5,537
Total
Beginning balance	83,979us-gaap_OtherRealEstate	146,090us-gaap_OtherRealEstate
Additions	66,282us-gaap_OtherRealEstateAdditions	92,942us-gaap_OtherRealEstateAdditions
Sales	(87,688)us-gaap_OtherRealEstateDisposals	(132,912)us-gaap_OtherRealEstateDisposals
Writedowns	(16,072)	(22,141)
Other Real Estate Transfers	0fcnca_OtherRealEstateTransfers
Ending balance	93,436us-gaap_OtherRealEstate	83,979us-gaap_OtherRealEstate
Bancorporation
Covered
Additions	1,300
Noncovered
Additions	34,000
Total
Additions	35,300
1st Financial
Covered
Additions	0
Noncovered
Additions	11,600
Total
Additions	$ 11,600

Other real estate covered that has transfered to non covered due to expiration of loss share agreements.

No definition available.

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- Definition

Other real estate non covered that has been transfered in from covered due to expiring loss share agreements.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Other real estate balances that have transfered between the categories of covered and non covered.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10(4))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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- Definition

Additions of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

No definition available.

+ Details

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- Definition

Carrying amount of other real estate covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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- Definition

Additions of other real estate covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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- Definition

Disposals of other real estate covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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- Details

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- Definition

Valuation adjustments made to other real estate covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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- Definition

Disposals of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Carrying amount of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Additions of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Disposals of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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- Details

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- Definition

Valuation adjustments made to other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Details

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- Definition

Valuation adjustments made to other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Details

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- Details

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