Loans and Allowance for Loan Losses - Impaired Loans Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	$ 44,531	$ 52,140
Recorded Investment with Allowance	39,856	47,482
Related Allowance	3,570	4,276
Average Recorded Investment	43,509	47,601
Non-residential real estate owner occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	993	7,058
Recorded Investment with Allowance	924	6,094
Related Allowance	34	232
Average Recorded Investment	700	6,237
Non-residential real estate other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	25,724	20,535
Recorded Investment with Allowance	24,216	20,340
Related Allowance	2,240	1,581
Average Recorded Investment	25,871	20,496
Residential real estate permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	1,263	1,299
Recorded Investment with Allowance	1,068	1,089
Related Allowance	57	30
Average Recorded Investment	1,298	1,184
Residential real estate all other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	2,423	4,365
Recorded Investment with Allowance	2,020	4,047
Related Allowance	381	1,344
Average Recorded Investment	3,668	4,149
Non-consumer non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	1,931	3,144
Recorded Investment with Allowance	1,599	2,539
Related Allowance	396	677
Average Recorded Investment	1,508	1,745
Consumer non-real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	413	447
Recorded Investment with Allowance	394	424
Related Allowance	67	77
Average Recorded Investment	444	364
Other loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	1,905	2,420
Recorded Investment with Allowance	1,782	2,265
Related Allowance	300	264
Average Recorded Investment	1,911	1,975
Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	9,879	12,872
Recorded Investment with Allowance	7,853	10,684
Related Allowance	95	71
Average Recorded Investment	$ 8,109	$ 11,451

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5212-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5258-111524

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953550-111524

+ Details

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- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

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- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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