Summary of Significant Accounting Policies (Additional Cash Flow Information) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Cash paid for interest	$ 14,705us-gaap_InterestPaid	$ 22,449us-gaap_InterestPaid	$ 29,378us-gaap_InterestPaid
Cash paid for income tax	62,976us-gaap_IncomeTaxesPaid	49,514us-gaap_IncomeTaxesPaid	58,950us-gaap_IncomeTaxesPaid
Transfer of securities from available for sale to held to maturity	0	0	2,266,195
Unsettled purchases of securities	0cfr_UnsettledSecurityTransactions	16,241cfr_UnsettledSecurityTransactions	90,073cfr_UnsettledSecurityTransactions
Loans foreclosed and transferred to other real estate owned and foreclosed assets	4,363us-gaap_TransferOfOtherRealEstate	6,870us-gaap_TransferOfOtherRealEstate	7,817us-gaap_TransferOfOtherRealEstate
Premises and equipment transferred to other real estate owned and foreclosed assets	1,740us-gaap_OtherRealEstateDisposals	0us-gaap_OtherRealEstateDisposals	0us-gaap_OtherRealEstateDisposals
Loans to facilitate the sale of other real estate owned	102	678	0
Deferred gain on sale of building and parking garage	$ 0us-gaap_GainLossOnDispositionOfAssets	$ 768us-gaap_GainLossOnDispositionOfAssets	$ 0us-gaap_GainLossOnDispositionOfAssets

Transfer Of Investment Securities To Held To Maturity From Available For Sale

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- Definition

Unsettled Security Transactions

+ References

No definition available.

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- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

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-Topic 205

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

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-Paragraph 2

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- Definition

The amount of cash paid for interest during the period.

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-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

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- Definition

Mortgage loan related to property sales in noncash investing and financing activities.

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

-Publisher FASB

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-Topic 230

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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.

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- Definition

Value transferred out of real estate owned (REO) in noncash transactions.

+ References

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