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Allowance for Loan Losses - Summary of Allowance for Loan Losses and Recorded Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 2,162		$ 37
Allowance for Loan Losses, Collectively Evaluated for Impairment	50,051		48,110
Total Allowance for Loan Losses	52,213	$ 50,347	48,147	$ 48,814	$ 48,106	$ 47,911
Portfolio Loans, Individually Evaluated for Impairment	50,167		45,650
Portfolio Loans, Collectively Evaluated for Impairment	5,338,097		4,981,962
Total Portfolio Loans	5,388,264		5,027,612
Commercial and Industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	1,991		0
Allowance for Loan Losses, Collectively Evaluated for Impairment	12,780		10,853
Total Allowance for Loan Losses	14,771	14,740	10,853	13,308	13,711	13,668
Portfolio Loans, Individually Evaluated for Impairment	15,812		14,417
Portfolio Loans, Collectively Evaluated for Impairment	1,369,934		1,242,413
Total Portfolio Loans	1,385,746		1,256,830
Commercial Real Estate
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	15,978		15,043
Total Allowance for Loan Losses	15,978	15,266	15,043	19,018	19,071	20,164
Portfolio Loans, Individually Evaluated for Impairment	12,326		12,661
Portfolio Loans, Collectively Evaluated for Impairment	2,376,460		2,153,942
Total Portfolio Loans	2,388,786		2,166,603
Commercial Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	141		3
Allowance for Loan Losses, Collectively Evaluated for Impairment	11,560		12,622
Total Allowance for Loan Losses	11,701	10,825	12,625	7,671	6,869	6,093
Portfolio Loans, Individually Evaluated for Impairment	10,982		11,498
Portfolio Loans, Collectively Evaluated for Impairment	387,140		401,946
Total Portfolio Loans	398,122		413,444
Consumer Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	29		32
Allowance for Loan Losses, Collectively Evaluated for Impairment	8,389		8,368
Total Allowance for Loan Losses	8,418	8,261	8,400	7,027	6,723	6,333
Portfolio Loans, Individually Evaluated for Impairment	11,012		6,961
Portfolio Loans, Collectively Evaluated for Impairment	1,146,459		1,109,835
Total Portfolio Loans	1,157,471		1,116,796
Other Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	1		2
Allowance for Loan Losses, Collectively Evaluated for Impairment	1,344		1,224
Total Allowance for Loan Losses	1,345	$ 1,255	1,226	$ 1,790	$ 1,732	$ 1,653
Portfolio Loans, Individually Evaluated for Impairment	35		113
Portfolio Loans, Collectively Evaluated for Impairment	58,104		73,826
Total Portfolio Loans	$ 58,139		$ 73,939

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible 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 (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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

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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.

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