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Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Detail) - Consumer - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 1,203,105	$ 1,190,735
Percentage of Total	100.00%	100.00%
Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 1,190,717	$ 1,182,104
Percentage of Total	99.00%	99.30%
Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 12,388	$ 8,631
Percentage of Total	1.00%	0.70%
Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 650,544	$ 639,372
Percentage of Total	100.00%	100.00%
Residential Mortgage | Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 641,532	$ 633,743
Percentage of Total	98.60%	99.10%
Residential Mortgage | Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 9,012	$ 5,629
Percentage of Total	1.40%	0.90%
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 467,671	$ 470,845
Percentage of Total	100.00%	100.00%
Home Equity | Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 464,404	$ 467,943
Percentage of Total	99.30%	99.40%
Home Equity | Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 3,267	$ 2,902
Percentage of Total	0.70%	0.60%
Installment and Other Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 76,189	$ 73,939
Percentage of Total	100.00%	100.00%
Installment and Other Consumer | Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 76,080	$ 73,839
Percentage of Total	99.90%	99.80%
Installment and Other Consumer | Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 109	$ 100
Percentage of Total	0.10%	0.20%
Consumer Construction
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 8,701	$ 6,579
Percentage of Total	100.00%	100.00%
Consumer Construction | Performing Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 8,701	$ 6,579
Percentage of Total	100.00%	100.00%
Consumer Construction | Nonperforming Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivables, recorded investment	$ 0	$ 0
Percentage of Total	0.00%	0.00%

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- Definition

Loans and leases receivable gross carrying amount consumer percentage.

+ References

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. 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
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

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