Loans, Allowance for Loan Losses, and Credit Quality (Details 4) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Summary of nonaccrual loans
Nonaccrual loans	$ 467,611	$ 574,356
Commercial and industrial [Member]
Summary of nonaccrual loans
Nonaccrual loans	71,183	99,845
Commercial real estate [Member]
Summary of nonaccrual loans
Nonaccrual loans	193,495	223,927
Real estate construction [Member]
Summary of nonaccrual loans
Nonaccrual loans	72,782	94,929
Lease financing [Member]
Summary of nonaccrual loans
Nonaccrual loans	12,898	17,080
Total commercial [Member]
Summary of nonaccrual loans
Nonaccrual loans	350,358	435,781
Home equity [Member]
Summary of nonaccrual loans
Nonaccrual loans	46,777	51,712
Installment [Member]
Summary of nonaccrual loans
Nonaccrual loans	3,724	10,544
Total retail [Member]
Summary of nonaccrual loans
Nonaccrual loans	50,501	62,256
Residential mortgage [Member]
Summary of nonaccrual loans
Nonaccrual loans	66,752	76,319
Total consumer [Member]
Summary of nonaccrual loans
Nonaccrual loans	$ 117,253	$ 138,575