Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Allowance for loan losses	$ 34,840	$ 32,353
Net actuarial loss on defined benefit post-retirement benefit plans	26,263	14,070
Stock-based compensation	18,839	17,746
Bonus accrual	6,118	5,301
Gain on sale of assets	2,139cfr_DeferredTaxAssetsGainOnSaleOfAssets	2,234cfr_DeferredTaxAssetsGainOnSaleOfAssets
Partnerships	1,911	2,208
Transaction costs	1,794cfr_DeferredTaxAssetsTransactionCosts	565cfr_DeferredTaxAssetsTransactionCosts
Other	5,272us-gaap_DeferredTaxAssetsOther	4,489us-gaap_DeferredTaxAssetsOther
Total gross deferred tax assets	97,176us-gaap_DeferredTaxAssetsGross	78,966us-gaap_DeferredTaxAssetsGross
Net unrealized gain on securities available for sale and effective cash flow hedging derivatives	(102,626)	(89,689)
Premises and equipment	(20,039)	(21,192)
Defined benefit post-retirement benefit plans	(15,010)	(14,137)
Intangible assets	(6,143)	(7,253)
Leases	(4,952)	(4,237)
Reserve for medical insurance	(3,017)	(2,171)
Prepaid expenses	(1,639)	(1,618)
Other	(341)us-gaap_DeferredTaxLiabilitiesOther	(1,456)us-gaap_DeferredTaxLiabilitiesOther
Total gross deferred tax liabilities	(153,767)us-gaap_DeferredTaxLiabilities	(141,753)us-gaap_DeferredTaxLiabilities
Net deferred tax asset (liability)	$ (56,591)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (62,787)us-gaap_DeferredTaxAssetsLiabilitiesNet

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Deferred tax liabilities, defined benefit post-retirement benefit plans.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from postretirement benefits.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the provision for loan losses.

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Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences from leasing arrangements.

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Amount of deferred tax consequences attributable to taxable temporary differences derived from prepaid expenses.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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