Covered Loans in Non-Performing Status and Accruing Loans Past-Due 90 Days or More by Loan Class (Detail) (USD $) In Thousands	Jun. 30, 2011		Dec. 31, 2010
Covered under Loss Sharing Agreements with FDIC
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 14,979	[1]	$ 25,975	[1]
Accruing loans past-due 90 days or more	15,030	[1]	11,016	[1]
Covered under Loss Sharing Agreements with FDIC | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	7,374		14,172
Accruing loans past-due 90 days or more	562
Covered under Loss Sharing Agreements with FDIC | Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	5,476		10,635
Accruing loans past-due 90 days or more	263		60
Covered under Loss Sharing Agreements with FDIC | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	739		1,168
Accruing loans past-due 90 days or more	4,154
Covered under Loss Sharing Agreements with FDIC | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	563
Accruing loans past-due 90 days or more	6,783		8,648
Covered under Loss Sharing Agreements with FDIC | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	827
Accruing loans past-due 90 days or more	3,268		2,308
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 49,000		$ 60,000

[1] Covered loans accounted for under ASC Subtopic 310-30 are excluded from the above table as they are considered to be performing due to the application of the accretion method, in which these loans will accrete interest income over the remaining life of the loans using estimated cash flow analyses.