Loan Delinquency, including Nonaccrual Loans (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,789,154	$ 2,816,093
Non Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	22,204	16,950
60 - 89 days past due	7,443	11,880
> 90 days past due	45,007	44,875
Total Past due	74,654	73,705
Current	2,714,500	2,742,388
Total	2,789,154	2,816,093
> 90 days past due and still accruing	149	370
Non Covered Loans | Real estate-construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	2,146	1,754
60 - 89 days past due	0	3,782
> 90 days past due	13,213	8,973
Total Past due	15,359	14,509
Current	127,323	149,034
Total	142,682	163,543
> 90 days past due and still accruing	0	0
Non Covered Loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	2,683	2,241
60 - 89 days past due	2,835	1,573
> 90 days past due	8,741	11,684
Total Past due	14,259	15,498
Current	784,293	784,755
Total	798,552	800,253
> 90 days past due and still accruing	0	0
Non Covered Loans | Real estate-commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	10,260	3,202
60 - 89 days past due	2,008	3,979
> 90 days past due	15,523	16,435
Total Past due	27,791	23,616
Current	1,116,577	1,116,315
Total	1,144,368	1,139,931
> 90 days past due and still accruing	0	0
Non Covered Loans | Real estate-residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	5,644	7,671
60 - 89 days past due	1,901	1,930
> 90 days past due	5,306	5,127
Total Past due	12,851	14,728
Current	243,937	254,445
Total	256,788	269,173
> 90 days past due and still accruing	0	0
Non Covered Loans | Installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	214	456
60 - 89 days past due	98	48
> 90 days past due	181	120
Total Past due	493	624
Current	63,306	69,087
Total	63,799	69,711
> 90 days past due and still accruing	0	0
Non Covered Loans | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	917	1,260
60 - 89 days past due	383	392
> 90 days past due	1,894	2,166
Total Past due	3,194	3,818
Current	341,263	337,492
Total	344,457	341,310
> 90 days past due and still accruing	0	0
Non Covered Loans | All other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 days past due	340	366
60 - 89 days past due	218	176
> 90 days past due	149	370
Total Past due	707	912
Current	37,801	31,260
Total	38,508	32,172
> 90 days past due and still accruing	$ 149	$ 370