Changes in the Allowance for Loan and Lease Losses (Detail) (USD $) In Thousands	3 Months Ended					6 Months Ended		12 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Allowance for loan and lease losses:
Balance at beginning of period	$ 53,645	$ 57,235	$ 57,249	$ 57,811	$ 56,642	$ 57,235	$ 59,311	$ 59,311
Provision for loan and lease losses	5,756	647	9,741	6,287	6,158	6,403	17,536	33,564
Gross charge-offs	6,232	4,601	10,285	8,124	5,457	10,833	19,942	38,351
Recoveries	502	364	530	1,275	468	866	906	2,711
Total net charge-offs						9,967		35,640
Balance at end of period	53,671	53,645	57,235	57,249	57,811	53,671	57,811	57,235
Non Covered Loans | Commercial
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	1,528		2,017			1,528		2,017
Ending allowance on loans collectively evaluated for impairment	679		279			679		279
Impaired Financing Receivable, Related Allowance	2,207		2,296			2,207		2,296
Loans and Leases:
Ending balance of loans individually evaluated for impairment	7,423		12,175			7,423		12,175
Ending balance of loans collectively evaluated for impairment	2,395		1,554			2,395		1,554
Recorded Investment	9,818		13,729			9,818		13,729
Commercial
Allowance for loan and lease losses:
Balance at beginning of period		10,138				10,138	18,590	18,590
Provision for loan and lease losses						1,930		4,252
Gross charge-offs						815		13,324
Recoveries						322		620
Total net charge-offs						493		12,704
Balance at end of period	11,575		10,138			11,575		10,138
Non Covered Loans | Real estate-construction
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	4,387		3,716			4,387		3,716
Ending allowance on loans collectively evaluated for impairment	41		7			41		7
Impaired Financing Receivable, Related Allowance	4,428		3,723			4,428		3,723
Loans and Leases:
Ending balance of loans individually evaluated for impairment	19,377		19,294			19,377		19,294
Ending balance of loans collectively evaluated for impairment	169		38			169		38
Recorded Investment	19,546		19,332			19,546		19,332
Real estate-construction
Allowance for loan and lease losses:
Balance at beginning of period		8,326				8,326	8,143	8,143
Provision for loan and lease losses						1,841		8,778
Gross charge-offs						2,403		8,619
Recoveries						27		24
Total net charge-offs						2,376		8,595
Balance at end of period	7,791		8,326			7,791		8,326
Non Covered Loans | Real estate-commercial
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	4,021		4,347			4,021		4,347
Ending allowance on loans collectively evaluated for impairment	351		196			351		196
Impaired Financing Receivable, Related Allowance	4,372		4,543			4,372		4,543
Loans and Leases:
Ending balance of loans individually evaluated for impairment	28,537		31,260			28,537		31,260
Ending balance of loans collectively evaluated for impairment	3,502		2,864			3,502		2,864
Recorded Investment	32,039		34,124			32,039		34,124
Real estate-commercial
Allowance for loan and lease losses:
Balance at beginning of period		14,917				14,917	15,190	15,190
Provision for loan and lease losses						6,205		6,836
Gross charge-offs						4,880		8,191
Recoveries						73		1,082
Total net charge-offs						4,807		7,109
Balance at end of period	16,315		14,917			16,315		14,917
Non Covered Loans | Real estate-residential
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	93		122			93		122
Ending allowance on loans collectively evaluated for impairment	69		149			69		149
Impaired Financing Receivable, Related Allowance	162		271			162		271
Loans and Leases:
Ending balance of loans individually evaluated for impairment	2,088		1,912			2,088		1,912
Ending balance of loans collectively evaluated for impairment	4,564		4,607			4,564		4,607
Recorded Investment	6,652		6,519			6,652		6,519
Real estate-residential
Allowance for loan and lease losses:
Balance at beginning of period		8,907				8,907	5,308	5,308
Provision for loan and lease losses						(4,356)		5,268
Gross charge-offs						514		1,693
Recoveries						38		24
Total net charge-offs						476		1,669
Balance at end of period	4,075		8,907			4,075		8,907
Non Covered Loans | Installment
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0		0			0		0
Ending allowance on loans collectively evaluated for impairment	9		4			9		4
Impaired Financing Receivable, Related Allowance	9		4			9		4
Loans and Leases:
Ending balance of loans individually evaluated for impairment	113		0			113		0
Ending balance of loans collectively evaluated for impairment	335		150			335		150
Recorded Investment	448		150			448		150
Installment
Allowance for loan and lease losses:
Balance at beginning of period		1,981				1,981	2,159	2,159
Provision for loan and lease losses						(119)		457
Gross charge-offs						249		1,154
Recoveries						180		519
Total net charge-offs						69		635
Balance at end of period	1,793		1,981			1,793		1,981
Non Covered Loans | Home equity
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	2		0			2		0
Ending allowance on loans collectively evaluated for impairment	69		82			69		82
Impaired Financing Receivable, Related Allowance	71		82			71		82
Loans and Leases:
Ending balance of loans individually evaluated for impairment	101		0			101		0
Ending balance of loans collectively evaluated for impairment	2,375		2,553			2,375		2,553
Recorded Investment	2,476		2,553			2,476		2,553
Home equity
Allowance for loan and lease losses:
Balance at beginning of period		10,939				10,939	8,063	8,063
Provision for loan and lease losses						242		6,183
Gross charge-offs						1,185		3,499
Recoveries						37		192
Total net charge-offs						1,148		3,307
Balance at end of period	10,033		10,939			10,033		10,939
Non Covered Loans | All other
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0		0			0		0
Ending allowance on loans collectively evaluated for impairment	0		0			0		0
Impaired Financing Receivable, Related Allowance	0		0			0		0
Loans and Leases:
Ending balance of loans individually evaluated for impairment	0		0			0		0
Ending balance of loans collectively evaluated for impairment	0		0			0		0
Recorded Investment	0		0			0		0
All other
Allowance for loan and lease losses:
Balance at beginning of period		2,027				2,027	1,858	1,858
Provision for loan and lease losses						660		1,790
Gross charge-offs						787		1,871
Recoveries						189		250
Total net charge-offs						598		1,621
Balance at end of period	2,089		2,027			2,089		2,027
Non Covered Loans
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	10,031		10,202			10,031		10,202
Ending allowance on loans collectively evaluated for impairment	1,218		717			1,218		717
Impaired Financing Receivable, Related Allowance	11,249		10,919			11,249		10,919
Loans and Leases:
Ending balance of loans individually evaluated for impairment	57,639		64,641			57,639		64,641
Ending balance of loans collectively evaluated for impairment	13,340		11,766			13,340		11,766
Recorded Investment	$ 70,979		$ 76,407			$ 70,979		$ 76,407