Loans and Allowance for Credit Losses - Schedule of Activity in Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Impaired [Line Items]
Beginning balance	$ 48,867	$ 32,054
(Charge-offs)/recoveries	215	(116)
Payments	(3,741)	(3,054)
Additions	1,234	2,094
Ending balance	46,575	30,978
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	22,443	12,660
(Charge-offs)/recoveries	123	(27)
Payments	(1,133)	(1,286)
Additions	188	668
Ending balance	21,621	12,015
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	22,639	18,422
(Charge-offs)/recoveries	121	(2)
Payments	(2,531)	(1,722)
Additions	730	949
Ending balance	20,959	17,647
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	1,441	473
(Charge-offs)/recoveries	(30)	(87)
Payments	(49)	(12)
Additions	294	472
Ending balance	1,656	846
Residential [Member]
Financing Receivable, Impaired [Line Items]
Beginning balance	2,344	499
(Charge-offs)/recoveries	1	0
Payments	(28)	(34)
Additions	22	5
Ending balance	$ 2,339	$ 470