Loans - Investment in Loans by Portfolio Segment and Based on Impairment (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance, Beginning balance	$ 19,087	$ 17,712
Provision (recovery) for loan losses	1,475	2,155
Charge-offs	(1,870)	(3,187)
Recoveries	278	223
Allowance, Ending balance	18,970	16,903
Allowance, Loans individually evaluated for impairment	1,732	3,022	$ 3,016
Allowance, Loans collectively evaluated for impairment	17,238		16,071
Period-end balances, Loans individually evaluated for impairment	27,839		31,548
Period-end balances, Loans collectively evaluated for impairment	1,821,087		1,487,929
Total loans	1,850,364		1,519,477
Loans Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Period-end balances, Loans acquired with deteriorated credit quality	1,438
Commercial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance, Beginning balance	10,824	8,077
Provision (recovery) for loan losses	522	2,724
Charge-offs	(1,311)	(2,346)
Recoveries	147	66
Allowance, Ending balance	10,182	8,521
Allowance, Loans individually evaluated for impairment	19	1,029	1,271
Allowance, Loans collectively evaluated for impairment	10,163		9,553
Period-end balances, Loans individually evaluated for impairment	2,685		6,018
Period-end balances, Loans collectively evaluated for impairment	704,241		498,240
Total loans	708,364		504,258
Commercial Loans [Member] \| Loans Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Period-end balances, Loans acquired with deteriorated credit quality	1,438
Residential Mortgage Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance, Beginning balance	5,538	6,630
Provision (recovery) for loan losses	570	(594)
Charge-offs	(230)	(362)
Recoveries	34	62
Allowance, Ending balance	5,912	5,736
Allowance, Loans individually evaluated for impairment	1,231	1,407	1,245
Allowance, Loans collectively evaluated for impairment	4,681		4,293
Period-end balances, Loans individually evaluated for impairment	16,902		17,485
Period-end balances, Loans collectively evaluated for impairment	873,883		781,136
Total loans	890,785		798,621
Consumer Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance, Beginning balance	2,725	3,005
Provision (recovery) for loan losses	383	25
Charge-offs	(329)	(479)
Recoveries	97	95
Allowance, Ending balance	2,876	2,646
Allowance, Loans individually evaluated for impairment	482	$ 586	500
Allowance, Loans collectively evaluated for impairment	2,394		2,225
Period-end balances, Loans individually evaluated for impairment	8,252		8,045
Period-end balances, Loans collectively evaluated for impairment	242,963		208,553
Total loans	$ 251,215		$ 216,598

Provision for recovery of loan losses.

No definition available.

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- Definition

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

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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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

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

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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
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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
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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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