Loans and Leases and the allowance for credit losses (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 9,843,549	$ 3,681,488
Carrying amount	8,699,875	3,337,725
Commercial, financial, leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	1,341,567	337,969
Commercial real estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	4,267,754	1,420,239
Residential real estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	959,714	348,225
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 2,130,840	$ 1,231,292