Impaired Loans Disaggregated by Class Average Recorded Investment and Interest Income Recognized (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 59,025	$ 168,311	$ 62,679	$ 175,785
Average Recorded Investment	1,111	1,522	3,456	2,815
Real Estate Loan [Member] | Retail [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,597	8,754	2,162	9,733
Average Recorded Investment	47	27	95	78
Real Estate Loan [Member] | Land [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,054	16,376	2,134	22,192
Average Recorded Investment	45	12	136	12
Real Estate Loan [Member] | Other [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	534	21,768	937	21,879
Average Recorded Investment	5	282	38	372
Real Estate Loan [Member] | Construction [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	7,868	11,057	8,016	11,201
Average Recorded Investment	29	272	207	317
Real Estate Loan [Member] | Residential Property [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	3,279	2,364	3,265	2,386
Average Recorded Investment	34	8	118	8
Commercial and Industrial Loans [Member] | Unsecured [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	13,723	18,972	14,079	19,554
Average Recorded Investment	214	82	644	148
Commercial and Industrial Loans [Member] | Secured by Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	19,990	66,108	21,834	64,667
Average Recorded Investment	342	813	1,300	1,809
Commercial and Industrial Loans [Member] | Commercial Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,555	2,398	1,742	2,631
Average Recorded Investment	16	2	46	5
Commercial and Industrial Loans [Member] | SBA Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	6,168	19,333	7,489	20,256
Average Recorded Investment	330	23	813	63
Consumer Loans [Member] | Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,257	1,181	1,021	1,286
Average Recorded Investment	$ 49	$ 1	$ 59	$ 3