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

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-Publisher FASB

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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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Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				$ 46,255				$ 46,484	$ 46,255	$ 46,484
Charge-offs									(6,353)	(15,576)
Recoveries									6,294	7,036
Net (Charge-offs)/ Recoveries									(59)	(8,540)
Provision for loan losses	1,106us-gaap_ProvisionForLoanAndLeaseLosses	1,454us-gaap_ProvisionForLoanAndLeaseLosses	(1,134)us-gaap_ProvisionForLoanAndLeaseLosses	289us-gaap_ProvisionForLoanAndLeaseLosses	1,562us-gaap_ProvisionForLoanAndLeaseLosses	3,419us-gaap_ProvisionForLoanAndLeaseLosses	1,023us-gaap_ProvisionForLoanAndLeaseLosses	2,307us-gaap_ProvisionForLoanAndLeaseLosses	1,715us-gaap_ProvisionForLoanAndLeaseLosses	8,311us-gaap_ProvisionForLoanAndLeaseLosses	22,815us-gaap_ProvisionForLoanAndLeaseLosses
Balance at End of Year	47,911				46,255				47,911	46,255	46,484
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				18,921				25,246	18,921	25,246
Charge-offs									(2,041)	(4,601)
Recoveries									1,798	3,388
Net (Charge-offs)/ Recoveries									(243)	(1,213)
Provision for loan losses									1,486	(5,112)
Balance at End of Year	20,164				18,921				20,164	18,921
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				14,433				7,759	14,433	7,759
Charge-offs									(1,267)	(2,714)
Recoveries									3,647	2,142
Net (Charge-offs)/ Recoveries									2,380	(572)
Provision for loan losses									(3,145)	7,246
Balance at End of Year	13,668				14,433				13,668	14,433
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				5,374				7,500	5,374	7,500
Charge-offs									(712)	(4,852)
Recoveries									146	531
Net (Charge-offs)/ Recoveries									(566)	(4,321)
Provision for loan losses									1,285	2,195
Balance at End of Year	6,093				5,374				6,093	5,374
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				6,362				5,058	6,362	5,058
Charge-offs									(1,200)	(2,407)
Recoveries									350	651
Net (Charge-offs)/ Recoveries									(850)	(1,756)
Provision for loan losses									821	3,060
Balance at End of Year	6,333				6,362				6,333	6,362
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of year				1,165				921	1,165	921
Charge-offs									(1,133)	(1,002)
Recoveries									353	324
Net (Charge-offs)/ Recoveries									(780)	(678)
Provision for loan losses									1,268	922
Balance at End of Year	$ 1,653				$ 1,165				$ 1,653	$ 1,165