Loans (Activity in Allowance for Loan Losses by Portfolio Segment) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 92,438	$ 104,453	$ 110,147
Provision for loan losses	16,314us-gaap_ProvisionForLoanAndLeaseLosses	20,582us-gaap_ProvisionForLoanAndLeaseLosses	10,080us-gaap_ProvisionForLoanAndLeaseLosses
Charge-offs	(28,485)	(44,797)	(33,040)
Recoveries	19,275	12,200	17,266
Net charge-offs	(9,210)	(32,597)	(15,774)
Ending balance	99,542	92,438	104,453
Loans individually evaluated for impairment	13,000	20,596	17,537
Loans collectively evaluated for impairment	86,542	71,842	86,916
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	52,790	54,164	42,774
Provision for loan losses	10,550	27,970	25,013
Charge-offs	(13,820)	(32,932)	(18,493)
Recoveries	9,672	3,588	4,870
Net charge-offs	(4,148)	(29,344)	(13,623)
Ending balance	59,192	52,790	54,164
Loans individually evaluated for impairment	11,836	16,682	13,171
Loans collectively evaluated for impairment	47,356	36,108	40,993
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	22,590	29,346	20,912
Provision for loan losses	6,573	(6,631)	7,658
Charge-offs	(3,800)	(1,329)	(3,951)
Recoveries	1,800	1,204	4,727
Net charge-offs	(2,000)	(125)	776
Ending balance	27,163	22,590	29,346
Loans individually evaluated for impairment	1,164	3,914	4,366
Loans collectively evaluated for impairment	25,999	18,676	24,980
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	5,230	5,252	3,540
Provision for loan losses	681	697	2,350
Charge-offs	(1,097)	(1,047)	(1,495)
Recoveries	364	328	857
Net charge-offs	(733)	(719)	(638)
Ending balance	5,178	5,230	5,252
Loans individually evaluated for impairment	0	0	0
Loans collectively evaluated for impairment	5,178	5,230	5,252
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	5,010	3,507	12,635
Provision for loan losses	5,328	3,912	(6,839)
Charge-offs	(9,768)	(9,489)	(9,101)
Recoveries	7,439	7,080	6,812
Net charge-offs	(2,329)	(2,409)	(2,289)
Ending balance	8,009	5,010	3,507
Loans individually evaluated for impairment	0	0	0
Loans collectively evaluated for impairment	8,009	5,010	3,507
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	6,818	12,184	30,286
Provision for loan losses	(6,818)	(5,366)	(18,102)
Charge-offs	0	0	0
Recoveries	0	0	0
Net charge-offs	0	0	0
Ending balance	0	6,818	12,184
Loans individually evaluated for impairment	0	0	0
Loans collectively evaluated for impairment	$ 0	$ 6,818	$ 12,184

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Amount of other addition (reduction) in allowance reserve for credit loss.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

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

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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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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.

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Amount of expense related to estimated loss from loan and lease transactions.

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