Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 46,616	$ 45,936	$ 46,255	$ 46,484
Charge-offs	(3,746)	(2,929)	(4,721)	(7,063)
Recoveries	4,844	2,075	5,891	3,354
Net (Charge-offs)/ Recoveries	1,098	(854)	1,170	(3,709)
Provision for loan losses	(1,134)	1,023	(845)	3,330
Balance at End of Period	46,580	46,105	46,580	46,105
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	19,880	24,442	18,921	25,246
Charge-offs	(1,737)	(1,170)	(2,004)	(2,809)
Recoveries	1,294	1,572	1,834	2,322
Net (Charge-offs)/ Recoveries	(443)	402	(170)	(487)
Provision for loan losses	1,296	(1,360)	1,982	(1,275)
Balance at End of Period	20,733	23,484	20,733	23,484
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	13,979	8,676	14,433	7,759
Charge-offs	(743)	(563)	(1,033)	(1,923)
Recoveries	2,936	190	3,249	290
Net (Charge-offs)/ Recoveries	2,193	(373)	2,216	(1,633)
Provision for loan losses	(3,168)	820	(3,645)	2,997
Balance at End of Period	13,004	9,123	13,004	9,123
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,183	6,603	5,374	7,500
Charge-offs	(664)	(54)	(692)	(443)
Recoveries	324	2	375	55
Net (Charge-offs)/ Recoveries	(340)	(52)	(317)	(388)
Provision for loan losses	(84)	(739)	(298)	(1,300)
Balance at End of Period	4,759	5,812	4,759	5,812
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	6,408	5,259	6,362	5,058
Charge-offs	(425)	(743)	(547)	(1,237)
Recoveries	164	225	223	508
Net (Charge-offs)/ Recoveries	(261)	(518)	(324)	(729)
Provision for loan losses	558	1,914	667	2,326
Balance at End of Period	6,705	6,655	6,705	6,655
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,166	956	1,165	921
Charge-offs	(177)	(399)	(445)	(651)
Recoveries	126	86	210	179
Net (Charge-offs)/ Recoveries	(51)	(313)	(235)	(472)
Provision for loan losses	264	388	449	582
Balance at End of Period	$ 1,379	$ 1,031	$ 1,379	$ 1,031