Loans and leases and the allowance for credit losses (Details 2) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Changes in the allowance for credit losses
Beginning balance	$ 907,589		$ 902,941
Provision for credit losses	58,000		196,000
Net charge-offs
Charge-offs	(66,496)	(101,782)	(221,240)	(313,167)
Recoveries	9,432	8,835	30,824	44,113
Net charge-offs	(57,064)	(92,947)	(190,416)	(269,054)
Ending balance	908,525		908,525
Commercial, financial, leasing, etc. [Member]
Changes in the allowance for credit losses
Beginning balance	209,879		212,579
Provision for credit losses	23,145		44,957
Net charge-offs
Charge-offs	(12,073)		(41,023)
Recoveries	2,613		7,051
Net charge-offs	(9,460)		(33,972)
Ending balance	223,564		223,564
Real Estate Commercial [Member]
Changes in the allowance for credit losses
Beginning balance	401,111		400,562
Provision for credit losses	(545)		36,965
Net charge-offs
Charge-offs	(13,712)		(54,206)
Recoveries	839		4,372
Net charge-offs	(12,873)		(49,834)
Ending balance	387,693		387,693
Residential real estate loans [Member]
Changes in the allowance for credit losses
Beginning balance	87,341		86,351
Provision for credit losses	8,264		37,759
Net charge-offs
Charge-offs	(12,135)		(44,174)
Recoveries	1,750		5,284
Net charge-offs	(10,385)		(38,890)
Ending balance	85,220		85,220
Consumer [Member]
Changes in the allowance for credit losses
Beginning balance	137,309		133,067
Provision for credit losses	27,231		74,847
Net charge-offs
Charge-offs	(28,576)		(81,837)
Recoveries	4,230		14,117
Net charge-offs	(24,346)		(67,720)
Ending balance	140,194		140,194
Unallocated [Member]
Changes in the allowance for credit losses
Beginning balance	71,949		70,382
Provision for credit losses	(95)		1,472
Net charge-offs
Ending balance	$ 71,854		$ 71,854