Loans and Leases and the Allowance for Credit Losses - Interest Income Recognized on Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Loans And Leases Receivable [Line Items]
Average recorded investment	$ 1,055,874	$ 1,087,554	$ 1,056,860	$ 1,100,021
Interest income recognized, Total	11,479	11,415	19,295	16,995
Interest income recognized, Cash basis	8,816	8,693	14,005	11,452
Commercial, Financial, Leasing, etc. [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	183,544	161,311	172,637	164,779
Interest income recognized, Total	3,408	743	5,842	1,152
Interest income recognized, Cash basis	3,408	743	5,842	1,152
Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	201,236	180,199	197,546	179,213
Interest income recognized, Total	409	1,238	712	1,556
Interest income recognized, Cash basis	409	1,238	712	1,556
Residential Builder and Developer [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	162,567	262,254	173,535	271,903
Interest income recognized, Total	518	385	658	726
Interest income recognized, Cash basis	384	252	449	431
Other Commercial Construction [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	97,975	109,037	98,160	107,151
Interest income recognized, Total	2,479	4,840	3,114	5,010
Interest income recognized, Cash basis	2,479	4,840	3,114	5,010
Residential [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	185,751	127,258	186,582	126,880
Interest income recognized, Total	1,934	1,315	3,404	2,657
Interest income recognized, Cash basis	1,401	810	2,323	1,688
Residential Alt-A [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	151,977	174,181	154,461	177,623
Interest income recognized, Total	1,670	1,753	3,410	3,596
Interest income recognized, Cash basis	516	527	1,107	1,073
Home Equity Lines and Loans [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	12,619	11,237	12,544	10,593
Interest income recognized, Total	165	164	332	330
Interest income recognized, Cash basis	39	46	78	88
Automobile [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	44,641	52,200	46,134	52,799
Interest income recognized, Total	740	871	1,516	1,769
Interest income recognized, Cash basis	131	190	277	368
Other [Member]
Loans And Leases Receivable [Line Items]
Average recorded investment	15,564	9,877	15,261	9,080
Interest income recognized, Total	156	106	307	199
Interest income recognized, Cash basis	$ 49	$ 47	$ 103	$ 86