Loans and Leases and the Allowance for Credit Losses - Interest Income Recognized on Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Loans And Leases Receivable [Line Items]
Average recorded investment	$ 981,278	$ 1,017,603	$ 1,031,664	$ 1,072,657
Interest income recognized, Total	5,845	6,784	25,140	23,779
Interest income recognized, Cash basis	3,411	4,060	17,416	15,512
Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	149,357	141,166	164,877	155,627
Interest income recognized, Total	516	1,507	6,358	2,659
Interest income recognized, Cash basis	516	1,507	6,358	2,659
Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	205,971	180,009	200,354	179,524
Interest income recognized, Total	716	531	1,428	2,087
Interest income recognized, Cash basis	716	531	1,428	2,087
Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	130,855	237,847	159,308	260,858
Interest income recognized, Total	213	476	871	1,202
Interest income recognized, Cash basis	188	370	637	801
Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	95,486	84,604	97,268	100,242
Interest income recognized, Total	208	9	3,322	5,019
Interest income recognized, Cash basis	208	9	3,322	5,019
Residential [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	180,995	131,114	184,719	128,646
Interest income recognized, Total	1,391	1,269	4,795	3,926
Interest income recognized, Cash basis	865	765	3,188	2,453
Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	147,056	167,780	151,992	174,390
Interest income recognized, Total	1,763	1,836	5,173	5,432
Interest income recognized, Cash basis	692	593	1,799	1,666
Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	12,810	11,949	12,633	11,024
Interest income recognized, Total	167	172	499	502
Interest income recognized, Cash basis	49	48	127	136
Automobile [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	42,957	51,138	45,075	52,249
Interest income recognized, Total	710	863	2,226	2,632
Interest income recognized, Cash basis	127	185	404	553
Other [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	15,791	11,996	15,438	10,097
Interest income recognized, Total	161	121	468	320
Interest income recognized, Cash basis	$ 50	$ 52	$ 153	$ 138