Loans and leases and the allowance for credit losses (Details 9) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Modification	Mar. 31, 2011 Modification
Loan modification activities that were considered troubled debt restructurings
Number of modifications	445	485
Pre-modification Recorded Investment	$ 26,628	$ 147,951
Post-modification Recorded Investment	26,661	140,449
Financial effects of modification recorded investment	33	(7,502)
Financial effects of modification interest	(483)	(1,512)
Principal deferral [Member] | Commercial, financial, leasing, etc. [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	9	13
Pre-modification Recorded Investment	2,812	1,349
Post-modification Recorded Investment	2,954	1,334
Financial effects of modification recorded investment	142	(15)
Principal deferral [Member] | Commercial real estate loans [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	2	9
Pre-modification Recorded Investment	2,425	6,625
Post-modification Recorded Investment	2,405	6,597
Financial effects of modification recorded investment	(20)	(28)
Principal deferral [Member] | Residential builder and developer [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	5	1
Pre-modification Recorded Investment	6,822	3,424
Post-modification Recorded Investment	6,034	3,424
Financial effects of modification recorded investment	(788)
Principal deferral [Member] | Other commercial construction [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications		1
Pre-modification Recorded Investment		2,275
Post-modification Recorded Investment		2,269
Financial effects of modification recorded investment		(6)
Principal deferral [Member] | Residential real estate excluding Alt-A [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	15	3
Pre-modification Recorded Investment	1,505	124
Post-modification Recorded Investment	1,588	138
Financial effects of modification recorded investment	83	14
Principal deferral [Member] | Residential Alt-A [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	3
Pre-modification Recorded Investment	397
Post-modification Recorded Investment	407
Financial effects of modification recorded investment	10
Principal deferral [Member] | Home equity lines and loans [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	1
Pre-modification Recorded Investment	117
Post-modification Recorded Investment	117
Principal deferral [Member] | Automobile [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	153	204
Pre-modification Recorded Investment	1,885	3,493
Post-modification Recorded Investment	1,885	3,493
Principal deferral [Member] | Other [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	52	10
Pre-modification Recorded Investment	647	74
Post-modification Recorded Investment	647	74
Other [Member] | Commercial, financial, leasing, etc. [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	1
Pre-modification Recorded Investment	972
Post-modification Recorded Investment	1,098
Financial effects of modification recorded investment	126
Other [Member] | Residential builder and developer [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications		4
Pre-modification Recorded Investment		116,002
Post-modification Recorded Investment		108,394
Financial effects of modification recorded investment		(7,608)
Other [Member] | Automobile [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	10	26
Pre-modification Recorded Investment	19	107
Post-modification Recorded Investment	19	107
Other [Member] | Other [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	9	1
Pre-modification Recorded Investment	49	11
Post-modification Recorded Investment	49	11
Interest Rate Reduction [Member] | Residential real estate excluding Alt-A [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications		8
Pre-modification Recorded Investment		1,059
Post-modification Recorded Investment		1,079
Financial effects of modification recorded investment		20
Financial effects of modification interest		(50)
Interest Rate Reduction [Member] | Home equity lines and loans [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	1
Pre-modification Recorded Investment	144
Post-modification Recorded Investment	144
Financial effects of modification interest	(6)
Interest Rate Reduction [Member] | Automobile [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	4	4
Pre-modification Recorded Investment	57	44
Post-modification Recorded Investment	57	44
Financial effects of modification interest	(4)	(3)
Interest Rate Reduction [Member] | Other [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	3
Pre-modification Recorded Investment	23
Post-modification Recorded Investment	23
Financial effects of modification interest	(3)
Combination of concession types [Member] | Commercial, financial, leasing, etc. [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	1
Pre-modification Recorded Investment	45
Post-modification Recorded Investment	44
Financial effects of modification recorded investment	(1)
Financial effects of modification interest	(33)
Combination of concession types [Member] | Residential builder and developer [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	2	1
Pre-modification Recorded Investment	2,350	798
Post-modification Recorded Investment	2,726	790
Financial effects of modification recorded investment	376	(8)
Combination of concession types [Member] | Residential real estate excluding Alt-A [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	18	30
Pre-modification Recorded Investment	2,936	7,907
Post-modification Recorded Investment	3,007	7,999
Financial effects of modification recorded investment	71	92
Financial effects of modification interest	(200)	(757)
Combination of concession types [Member] | Residential Alt-A [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	8	9
Pre-modification Recorded Investment	1,360	1,602
Post-modification Recorded Investment	1,394	1,638
Financial effects of modification recorded investment	34	36
Financial effects of modification interest	(5)	(210)
Combination of concession types [Member] | Home equity lines and loans [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	2	2
Pre-modification Recorded Investment	235	70
Post-modification Recorded Investment	235	71
Financial effects of modification recorded investment		1
Financial effects of modification interest	(24)	(36)
Combination of concession types [Member] | Automobile [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	112	122
Pre-modification Recorded Investment	1,609	2,861
Post-modification Recorded Investment	1,609	2,861
Financial effects of modification interest	(172)	(436)
Combination of concession types [Member] | Other [Member]
Loan modification activities that were considered troubled debt restructurings
Number of modifications	34	37
Pre-modification Recorded Investment	219	126
Post-modification Recorded Investment	219	126
Financial effects of modification interest	$ (36)	$ (20)