Loans and leases and the allowance for credit losses (Details 5) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Summary of Loan grades
Loans and leases, net of unearned discount	$ 58,541,229	$ 51,990,382
Pass [Member] | Commercial, financial, leasing [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	14,154,538	12,371,138
Pass [Member] | Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	18,403,985	15,831,104
Pass [Member] | Residential builder and developer [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	1,255,712	693,110
Pass [Member] | Other commercial construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	2,329,099	2,253,589
Criticized Accrual [Member] | Commercial, financial, leasing [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	722,733	832,733
Criticized Accrual [Member] | Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	912,811	891,655
Criticized Accrual [Member] | Residential builder and developer [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	226,666	311,932
Criticized Accrual [Member] | Other commercial construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	427,278	519,651
Criticized Nonaccrual [Member] | Commercial, financial, leasing [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	163,621	186,739
Criticized Nonaccrual [Member] | Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	234,171	209,031
Criticized Nonaccrual [Member] | Residential builder and developer [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	359,152	346,448
Criticized Nonaccrual [Member] | Other commercial construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	114,852	126,641
Commercial, financial, leasing [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	15,040,892	13,390,610
Commercial real estate loans [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	24,263,726	21,183,161
Commercial Real Estate Excluding Residential Builder and Developer and Other Construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	19,550,967	16,931,790
Residential builder and developer [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	1,841,530	1,351,490
Other commercial construction [Member]
Summary of Loan grades
Loans and leases, net of unearned discount	$ 2,871,229	$ 2,899,881