Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 46,255	$ 46,484
Charge-offs	(974)	(4,134)
Recoveries	1,046	1,279
Net (Charge-offs)/ Recoveries	72	(2,855)
Provision for loan losses	289	2,307
Balance at End of Period	46,616	45,936
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	18,921	25,246
Charge-offs	(266)	(1,639)
Recoveries	540	749
Net (Charge-offs)/ Recoveries	274	(890)
Provision for loan losses	685	86
Balance at End of Period	19,880	24,442
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	14,433	7,759
Charge-offs	(290)	(1,360)
Recoveries	314	100
Net (Charge-offs)/ Recoveries	24	(1,260)
Provision for loan losses	(478)	2,177
Balance at End of Period	13,979	8,676
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,374	7,500
Charge-offs	(28)	(389)
Recoveries	50	53
Net (Charge-offs)/ Recoveries	22	(336)
Provision for loan losses	(213)	(561)
Balance at End of Period	5,183	6,603
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	6,362	5,058
Charge-offs	(123)	(494)
Recoveries	59	283
Net (Charge-offs)/ Recoveries	(64)	(211)
Provision for loan losses	110	412
Balance at End of Period	6,408	5,259
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,165	921
Charge-offs	(267)	(252)
Recoveries	83	94
Net (Charge-offs)/ Recoveries	(184)	(158)
Provision for loan losses	185	193
Balance at End of Period	$ 1,166	$ 956