Deferred Tax Assets and Deferred Tax Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets
Allowance for loan and lease losses	$ 50,013	$ 50,652
Other real estate owned	8,200	8,041
Interest rate swap agreements	6,467	0
Acquisition fair market value adjustments	5,302	4,151
Deferred compensation	5,024	4,837
Income tax credits and net operating loss carryforwards	4,652	2,778
Employee benefits	2,839	3,132
Other	4,290us-gaap_DeferredTaxAssetsOther	3,662us-gaap_DeferredTaxAssetsOther
Total gross deferred tax assets	86,787us-gaap_DeferredTaxAssetsGross	77,253us-gaap_DeferredTaxAssetsGross
Deferred tax liabilities
Available-for-sale securities	(17,716)	(5,402)
FHLB stock dividends	(10,342)	(10,359)
Deferred loan costs	(6,419)	(6,058)
Intangibles	(4,290)	(3,099)
Depreciation of premises and equipment	(2,358)	(3,939)
Interest rate swap agreements	0	(736)
Other	(3,925)us-gaap_DeferredTaxLiabilitiesOther	(4,111)us-gaap_DeferredTaxLiabilitiesOther
Total gross deferred tax liabilities	(45,050)us-gaap_DeferredIncomeTaxLiabilities	(33,704)us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax asset	$ 41,737us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 43,549us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred Tax Assets Fair Market Value Adjustments from Acquisitions

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from other real estate owned.

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Deferred tax liabilities stock dividends.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to other deductible tax carryforwards not separately disclosed.

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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 deferred financing costs.

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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 not separately disclosed.

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Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains in other comprehensive income.

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

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