Allowance for Loan Losses, Excluding PCI Loans, by Loan Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 20,258	$ 23,911	$ 20,227	$ 24,077
Provision for (recovery of) loan losses charged to operations	381	(2,439)	1,757	633
Loans charged off	(689)	(1,118)	(2,940)	(5,119)
Recoveries credited to allowance	252	915	1,112	2,019
Net (charge-offs) recoveries	(437)	(203)	(1,828)	(3,100)
Ending balance	20,127	21,159	20,127	21,159
Allowance Excluding Purchased Credit Impaired
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	20,144	23,493	20,169	23,322
Provision for (recovery of) loan losses charged to operations	400	(2,335)	1,766	733
Loans charged off	(689)	(1,118)	(2,940)	(5,119)
Recoveries credited to allowance	252	915	1,112	2,019
Net (charge-offs) recoveries	(437)	(203)	(1,828)	(3,100)
Ending balance	20,107	20,955	20,107	20,955
Commercial Loans \| Allowance Excluding Purchased Credit Impaired
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	12,995	16,747	13,010	16,090
Provision for (recovery of) loan losses charged to operations	6	(3,131)	754	(478)
Loans charged off	(150)	(558)	(1,111)	(2,839)
Recoveries credited to allowance	102	613	300	898
Net (charge-offs) recoveries	(48)	55	(811)	(1,941)
Ending balance	12,953	13,671	12,953	13,671
Consumer Real Estate \| Allowance Excluding Purchased Credit Impaired
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,468	6,123	6,489	6,597
Provision for (recovery of) loan losses charged to operations	20	561	136	592
Loans charged off	(130)	(219)	(622)	(1,184)
Recoveries credited to allowance	86	192	441	652
Net (charge-offs) recoveries	(44)	(27)	(181)	(532)
Ending balance	6,444	6,657	6,444	6,657
Consumer and Other \| Allowance Excluding Purchased Credit Impaired
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	681	623	670	635
Provision for (recovery of) loan losses charged to operations	374	235	876	619
Loans charged off	(409)	(341)	(1,207)	(1,096)
Recoveries credited to allowance	64	110	371	469
Net (charge-offs) recoveries	(345)	(231)	(836)	(627)
Ending balance	$ 710	$ 627	$ 710	$ 627

Provision for (Recovery of) Loan and Lease Losses

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount, after recoveries, of loans and leases that have been written-off.

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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 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 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

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-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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