Covered Commercial and Consumer Credit Exposure by Risk Attribute (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Covered loans	$ 1,242,730	$ 1,481,493
Commercial
Financing Receivable, Recorded Investment [Line Items]
Covered loans	251,753	334,039
Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Covered loans	159,323	225,088
Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Covered loans	28,341	35,768
Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Covered loans	44,444	60,090
Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Covered loans	19,645	13,093
Real estate-construction
Financing Receivable, Recorded Investment [Line Items]
Covered loans	40,811	42,743
Real estate-construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Covered loans	7,453	14,021
Real estate-construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Covered loans	13,019	5,743
Real estate-construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Covered loans	20,339	22,979
Real estate-construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Covered loans	0	0
Real estate-commercial
Financing Receivable, Recorded Investment [Line Items]
Covered loans	726,885	855,725
Real estate-commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Covered loans	384,580	476,140
Real estate-commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Covered loans	79,563	106,057
Real estate-commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Covered loans	253,858	268,651
Real estate-commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Covered loans	8,884	4,877
Real estate-residential
Financing Receivable, Recorded Investment [Line Items]
Covered loans	134,131	147,052
Real estate-residential | Performing
Financing Receivable, Recorded Investment [Line Items]
Covered loans	134,131	147,052
Real estate-residential | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Covered loans	0	0
Installment
Financing Receivable, Recorded Investment [Line Items]
Covered loans	15,197	21,071
Installment | Performing
Financing Receivable, Recorded Investment [Line Items]
Covered loans	15,197	21,071
Installment | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Covered loans	0	0
Home equity
Financing Receivable, Recorded Investment [Line Items]
Covered loans	68,664	73,695
Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Covered loans	67,507	72,204
Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Covered loans	1,157	1,491
All other
Financing Receivable, Recorded Investment [Line Items]
Covered loans	5,289	7,168
All other | Performing
Financing Receivable, Recorded Investment [Line Items]
Covered loans	5,289	7,168
All other | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Covered loans	$ 0	$ 0