Loans and Allowance for Credit Losses - Schedule of Activity in 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 [Line Items]
Beginning balance			$ 41,741
Provision	(400)	(3,693)	(363)	(2,848)
Ending balance	42,494		42,494
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	19,506	16,967	16,565	14,642
Charge-offs	(926)	(859)	(2,073)	(1,969)
Recoveries	794	1,314	1,586	2,029
Provision	(548)	(2,338)	2,748	382
Ending balance	18,826	15,084	18,826	15,084
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	19,310	28,446	22,401	31,289
Charge-offs	(1,039)	(1,065)	(1,207)	(2,801)
Recoveries	480	849	1,575	1,738
Provision	(987)	(1,635)	(5,005)	(3,631)
Ending balance	17,764	26,595	17,764	26,595
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	5,378	4,685	4,940	5,155
Charge-offs	(958)	(1,612)	(2,083)	(3,514)
Recoveries	841	1,174	1,662	2,408
Provision	728	597	1,470	795
Ending balance	5,989	4,844	5,989	4,844
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	3,359	3,383	3,239	3,677
Charge-offs	(220)	(454)	(199)	(711)
Recoveries	27	183	109	223
Provision	407	(317)	424	(394)
Ending balance	3,573	2,795	3,573	2,795
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance
Charge-offs
Recoveries
Provision
Ending balance
Loans and Leases Receivable Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	47,553	53,481	47,145	54,763
Charge-offs	(3,143)	(3,990)	(5,562)	(8,995)
Recoveries	2,142	3,520	4,932	6,398
Provision	(400)	(3,693)	(363)	(2,848)
Ending balance	$ 46,152	$ 49,318	$ 46,152	$ 49,318