Investment in Impaired Loans (Detail) (Non Covered Loans, USD $) In Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 70,979	$ 70,979	$ 76,407
Contractual Principal Balance	94,395	94,395	97,004
Related Allowance	10,031	10,031	10,202
Average Recorded Investment		74,681	76,926
Interest Income Recognized	171	381	2,164
Real estate-construction
Financing Receivable, Impaired [Line Items]
Recorded Investment	19,546	19,546	19,332
Contractual Principal Balance	28,719	28,719	26,719
Related Allowance	4,387	4,387	3,716
Average Recorded Investment		19,821	20,998
Interest Income Recognized	35	89	476
Real estate-construction | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,638	5,638	4,925
Contractual Principal Balance	12,238	12,238	8,458
Related Allowance	0	0	0
Average Recorded Investment		5,494	9,935
Interest Income Recognized	0	1	98
Real estate-construction | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	13,908	13,908	14,407
Contractual Principal Balance	16,481	16,481	18,261
Related Allowance	4,387	4,387	3,716
Average Recorded Investment		14,327	11,063
Interest Income Recognized	35	88	378
Commercial
Financing Receivable, Impaired [Line Items]
Recorded Investment	9,818	9,818	13,729
Contractual Principal Balance	12,736	12,736	18,098
Related Allowance	1,528	1,528	2,017
Average Recorded Investment		11,157	17,855
Interest Income Recognized	15	27	305
Commercial | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	6,706	6,706	9,375
Contractual Principal Balance	8,146	8,146	12,008
Related Allowance	0	0	0
Average Recorded Investment		7,858	7,432
Interest Income Recognized	15	27	228
Commercial | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,112	3,112	4,354
Contractual Principal Balance	4,590	4,590	6,090
Related Allowance	1,528	1,528	2,017
Average Recorded Investment		3,299	10,423
Interest Income Recognized	0	0	77
Real estate-commercial
Financing Receivable, Impaired [Line Items]
Recorded Investment	32,039	32,039	34,124
Contractual Principal Balance	42,754	42,754	41,459
Related Allowance	4,021	4,021	4,347
Average Recorded Investment		34,292	27,504
Interest Income Recognized	107	237	1,196
Real estate-commercial | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	18,586	18,586	17,431
Contractual Principal Balance	24,353	24,353	21,660
Related Allowance	0	0	0
Average Recorded Investment		19,088	14,113
Interest Income Recognized	68	132	804
Real estate-commercial | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	13,453	13,453	16,693
Contractual Principal Balance	18,401	18,401	19,799
Related Allowance	4,021	4,021	4,347
Average Recorded Investment		15,204	13,391
Interest Income Recognized	39	105	392
Real estate-residential
Financing Receivable, Impaired [Line Items]
Recorded Investment	6,652	6,652	6,519
Contractual Principal Balance	7,141	7,141	7,204
Related Allowance	93	93	122
Average Recorded Investment		6,587	8,045
Interest Income Recognized	9	20	107
Real estate-residential | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,857	5,857	5,854
Contractual Principal Balance	6,334	6,334	6,447
Related Allowance	0	0	0
Average Recorded Investment		5,713	6,611
Interest Income Recognized	5	10	84
Real estate-residential | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	795	795	665
Contractual Principal Balance	807	807	757
Related Allowance	93	93	122
Average Recorded Investment		874	1,434
Interest Income Recognized	4	10	23
Installment
Financing Receivable, Impaired [Line Items]
Recorded Investment	448	448	150
Contractual Principal Balance	461	461	179
Related Allowance	0	0	0
Average Recorded Investment		313	336
Interest Income Recognized	2	3	6
Installment | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	448	448	150
Contractual Principal Balance	461	461	179
Related Allowance	0	0	0
Average Recorded Investment		287	336
Interest Income Recognized	2	3	6
Installment | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Contractual Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment		26
Interest Income Recognized	0	0
Home equity
Financing Receivable, Impaired [Line Items]
Recorded Investment	2,476	2,476	2,553
Contractual Principal Balance	2,584	2,584	3,345
Related Allowance	2	2	0
Average Recorded Investment		2,511	2,188
Interest Income Recognized	3	5	74
Home equity | Loans with no related allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	2,375	2,375	2,553
Contractual Principal Balance	2,483	2,483	3,345
Related Allowance	0	0	0
Average Recorded Investment		2,444	2,188
Interest Income Recognized	2	4	74
Home equity | Loans with an allowance recorded
Financing Receivable, Impaired [Line Items]
Recorded Investment	101	101
Contractual Principal Balance	101	101
Related Allowance	2	2
Average Recorded Investment		67
Interest Income Recognized	$ 1	$ 1