Allowance for Loan Losses - Summary of Allowance for Loan Losses and Recorded Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 65	$ 97
Allowance for Loan Losses, Collectively Evaluated for Impairment	46,551	46,158
Total Allowance for Loan Losses	46,616	46,255	45,936	46,484
Portfolio Loans, Individually Evaluated for Impairment	48,654	52,856
Portfolio Loans, Collectively Evaluated for Impairment	3,579,242	3,513,343
Total Portfolio Loans	3,627,896	3,566,199
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	19,880	18,921
Total Allowance for Loan Losses	19,880	18,921	24,442	25,246
Portfolio Loans, Individually Evaluated for Impairment	22,219	26,968
Portfolio Loans, Collectively Evaluated for Impairment	1,585,739	1,580,788
Total Portfolio Loans	1,607,958	1,607,756
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	13,979	14,433
Total Allowance for Loan Losses	13,979	14,433	8,676	7,759
Portfolio Loans, Individually Evaluated for Impairment	9,766	9,580
Portfolio Loans, Collectively Evaluated for Impairment	875,104	832,869
Total Portfolio Loans	884,870	842,449
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	25
Allowance for Loan Losses, Collectively Evaluated for Impairment	5,183	5,349
Total Allowance for Loan Losses	5,183	5,374	6,603	7,500
Portfolio Loans, Individually Evaluated for Impairment	8,321	8,072
Portfolio Loans, Collectively Evaluated for Impairment	159,111	135,603
Total Portfolio Loans	167,432	143,675
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	50	53
Allowance for Loan Losses, Collectively Evaluated for Impairment	6,358	6,309
Total Allowance for Loan Losses	6,408	6,362	5,259	5,058
Portfolio Loans, Individually Evaluated for Impairment	8,200	8,079
Portfolio Loans, Collectively Evaluated for Impairment	894,875	896,357
Total Portfolio Loans	903,075	904,436
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	15	19
Allowance for Loan Losses, Collectively Evaluated for Impairment	1,151	1,146
Total Allowance for Loan Losses	1,166	1,165	956	921
Portfolio Loans, Individually Evaluated for Impairment	148	157
Portfolio Loans, Collectively Evaluated for Impairment	64,413	67,726
Total Portfolio Loans	$ 64,561	$ 67,883

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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The balance of financing receivables that were individually evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ 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 210.9-03.7(d))

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5074-111524

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-Name Accounting Standards Codification

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