Allowance for Loan Losses and Credit Quality - Schedule of Impaired Loans by Type and Interest Income Recognized (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	$ 28,046	$ 97,458
Unpaid Principal Balance, With Related Allowance	1,292	16,793
Unpaid Principal Balance	29,338	114,251
Recorded Investment, With no Related Allowance	21,359	64,953
Recorded Investment, With Related Allowance	1,292	11,288
Recorded Investment	22,651	76,241
Related Allowance, With no Related Allowance
Related Allowance, With Related Allowance	164	2,087
Related Allowance	164	2,087
Average Recorded Investment, With no Related Allowance	35,422	79,785
Average Recorded Investment, With Related Allowance	4,784	15,820
Average Recorded Investment	40,206	95,605
Interest Income Recognized, With no Related Allowance	29	20
Interest Income Recognized, With Related Allowance
Interest Income Recognized	29	20
Construction, Land Dev and Other Land [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	7,004	55,821
Unpaid Principal Balance, With Related Allowance
Unpaid Principal Balance	7,004	55,821
Recorded Investment, With no Related Allowance	3,747	35,952
Recorded Investment, With Related Allowance
Recorded Investment	3,747	35,952
Related Allowance, With no Related Allowance
Related Allowance, With Related Allowance
Related Allowance
Average Recorded Investment, With no Related Allowance	9,784	40,510
Average Recorded Investment, With Related Allowance	762	3,760
Average Recorded Investment	10,546	44,270
Interest Income Recognized, With no Related Allowance		5
Interest Income Recognized, With Related Allowance
Interest Income Recognized		5
Commercial & Industrial [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	1,275	4,668
Unpaid Principal Balance, With Related Allowance	384	1,662
Unpaid Principal Balance	1,659	6,330
Recorded Investment, With no Related Allowance	1,275	3,545
Recorded Investment, With Related Allowance	384	1,662
Recorded Investment	1,659	5,207
Related Allowance, With no Related Allowance
Related Allowance, With Related Allowance	46	202
Related Allowance	46	202
Average Recorded Investment, With no Related Allowance	2,046	1,766
Average Recorded Investment, With Related Allowance	713	994
Average Recorded Investment	2,759	2,760
Interest Income Recognized, With no Related Allowance
Interest Income Recognized, With Related Allowance
Interest Income Recognized
Commercial Real Estate Loans [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	15,938	27,377
Unpaid Principal Balance, With Related Allowance	419	15,131
Unpaid Principal Balance	16,357	42,508
Recorded Investment, With no Related Allowance	13,681	18,031
Recorded Investment, With Related Allowance	419	9,626
Recorded Investment	14,100	27,657
Related Allowance, With no Related Allowance
Related Allowance, With Related Allowance	25	1,885
Related Allowance	25	1,885
Average Recorded Investment, With no Related Allowance	18,151	30,981
Average Recorded Investment, With Related Allowance	2,915	9,012
Average Recorded Investment	21,066	39,993
Interest Income Recognized, With no Related Allowance
Interest Income Recognized, With Related Allowance
Interest Income Recognized
Other Loans Secured by 1-4 Family RE [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	2,897	4,661
Unpaid Principal Balance	2,897	4,661
Recorded Investment, With no Related Allowance	1,982	3,536
Recorded Investment	1,982	3,536
Related Allowance, With no Related Allowance
Related Allowance
Average Recorded Investment, With no Related Allowance	3,204	3,566
Average Recorded Investment, With Related Allowance		1,990
Average Recorded Investment	3,204	5,556
Interest Income Recognized, With no Related Allowance	8
Interest Income Recognized	8
Loans to Individuals, Family & Personal Expense [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	201	1,483
Unpaid Principal Balance	201	1,483
Recorded Investment, With no Related Allowance	137	635
Recorded Investment	137	635
Related Allowance, With no Related Allowance
Related Allowance
Average Recorded Investment, With no Related Allowance	262	191
Average Recorded Investment, With Related Allowance		64
Average Recorded Investment	262	255
Interest Income Recognized, With no Related Allowance	5
Interest Income Recognized	5
Indirect Consumer [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance		81
Unpaid Principal Balance		81
Recorded Investment, With no Related Allowance		79
Recorded Investment		79
Related Allowance, With no Related Allowance
Related Allowance
Average Recorded Investment, With no Related Allowance	163	138
Average Recorded Investment	163	138
Interest Income Recognized, With no Related Allowance	16	15
Interest Income Recognized	16	15
Other Loans and Overdrafts [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With no Related Allowance	731	3,367
Unpaid Principal Balance, With Related Allowance
Unpaid Principal Balance	731	3,367
Recorded Investment, With no Related Allowance	537	3,175
Recorded Investment, With Related Allowance
Recorded Investment	537	3,175
Related Allowance, With no Related Allowance
Related Allowance, With Related Allowance
Related Allowance
Average Recorded Investment, With no Related Allowance	1,812	2,535
Average Recorded Investment, With Related Allowance	61
Average Recorded Investment	1,873	2,535
Interest Income Recognized, With no Related Allowance
Interest Income Recognized, With Related Allowance
Interest Income Recognized
Secured Multifamily Residential [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Unpaid Principal Balance, With Related Allowance	489
Unpaid Principal Balance	489
Recorded Investment, With Related Allowance	489
Recorded Investment	489
Related Allowance, With Related Allowance	93
Related Allowance	93
Average Recorded Investment, With no Related Allowance		98
Average Recorded Investment, With Related Allowance	333
Average Recorded Investment	333	98
Interest Income Recognized, With Related Allowance
Interest Income Recognized

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