Fair Value Measurement (Details 5) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Financial assets:
Cash and due from banks, Carrying Amount	$ 191,965	$ 157,415	$ 221,851
Cash and due from banks, Fair Value	224,078	523,113
Investment securities, Carrying Amount	3,660,425	3,154,333
Investment securities, Fair Value	3,739,934	3,207,754
Loans held for sale, Carrying Amount	22,951	41,340	24,733
Loans held for sale reported at fair value	22,951	41,340
Net noncovered loans, Carrying Amount	7,299,032	7,087,398	6,985,095
Net noncovered loans, Fair Value	6,929,941	6,716,214
Net covered loans and loss share receivable, Carrying Amount	1,721,747	1,963,021	2,259,522
Net covered loans and loss share receivable, Fair Value	1,721,747	1,963,021
Accrued interest receivable, Carrying Amount	42,276	41,830
Accrued interest receivable, Fair Value	42,276	41,830
Mortgage servicing rights, Carrying Amount	20,744	21,317
Mortgage servicing rights, Fair Value	20,766	21,579
Derivative assets	47,809	47,764
Financial liabilities:
Deposits, Carrying Amount	11,340,939	11,268,006	11,515,171
Deposits, Fair Value	11,359,102	11,275,440
Federal funds purchased and securities sold under agreements to repurchase, Carrying Amount	809,570	777,585	744,055
Federal funds purchased and securities sold under agreements to repurchase, Fair Value	814,030	782,668
Wholesale borrowings, Carrying Amount	325,133	326,007	474,963
Wholesale borrowings, Fair Value	328,808	329,465
Accrued interest payable, Carrying Amount	5,851	6,560
Accrued interest payable, Fair Value	5,851	6,560
Derivative liabilities, Carrying Amount	72,037	72,824
Derivative liabilities, Fair Value	72,037	72,824
True up liability, Carrying Amount	12,196	12,061
True-up liability, Fair Value	$ 12,196	$ 12,061