Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Selected financial information by business segment
Net interest income	$ 21,614us-gaap_InterestIncomeExpenseNet	$ 20,228us-gaap_InterestIncomeExpenseNet
Provision for loan losses		350us-gaap_ProvisionForLoanLossesExpensed
Investment management and trust services	4,552	4,568
All other non-interest income	5,121	4,907
Non-interest expense	17,779us-gaap_NoninterestExpense	17,544us-gaap_NoninterestExpense
Income before income taxes	13,508	11,809
Income tax expense	4,253us-gaap_IncomeTaxExpenseBenefit	3,632us-gaap_IncomeTaxExpenseBenefit
Net income	9,255	8,177
Commercial banking
Selected financial information by business segment
Net interest income	21,560	20,181
Provision for loan losses		350
All other non-interest income	5,121	4,890
Non-interest expense	15,191	14,962
Income before income taxes	11,490	9,759
Income tax expense	3,534	2,903
Net income	7,956	6,856
Investment management and trust
Selected financial information by business segment
Net interest income	54	47
Investment management and trust services	4,552	4,568
All other non-interest income		17
Non-interest expense	2,588	2,582
Income before income taxes	2,018	2,050
Income tax expense	719	729
Net income	$ 1,299	$ 1,321

Amount of noninterest income excluding income from fees and commissions from investment management and trust services.

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Income from services rendered by trust departments or by any consolidated subsidiaries acting in a fiduciary capacity, including fees earned for (1) acting as an agent for fiduciary placement and loans and (2) custody or investment advisory services when such fees are not separately billed to the customer. This item excludes commissions and fees received for the accumulation or disbursement of funds deposited to Individual Retirement or Keogh plan accounts when such are not handled by the reporting entity's trust department.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13 (a))

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 13

-Article 9

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- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.4-08.(h))

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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- Definition

The net amount of operating interest income (expense).

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

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- Definition

Total aggregate amount of all noninterest expense.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.14)

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-Number 210

-Section 04

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-Article 9

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- Definition

Amount of expense related to loss from loan transactions.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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