Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financial assets
Cash and due from banks	$ 360,728	$ 454,958
Cash and due from banks, Fair Value	360,728	454,958
Interest-bearing deposits in other financial institutions	344,148	154,562
Interest-bearing deposits in other financial institutions, Fair value	344,148	154,562
Federal funds sold and securities purchased under agreements to resell	7,100	7,075
Federal funds sold and securities purchased under agreements to resell, Fair value	7,100	7,075
Investment securities available for sale, carrying amount	4,669,100	4,937,483
Investment securities available for sale, at fair value	4,669,100	4,937,483
Federal Home Loan Bank and Federal Reserve Bank stocks, carrying amount	177,808	191,188
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	177,808	191,188
Loans held for sale	196,570	249,195
Loans held for sale, fair value	199,087	255,201
Loans, net	13,897,427	13,652,920
Loans, net Fair value	13,432,367	12,751,626
Bank owned life insurance, carrying amount	546,894	544,764
Bank owned life insurance, Fair value	546,894	544,764
Accrued interest receivable, carrying amount	66,176	68,920
Accrued interest receivable, Fair value	66,176	68,920
Interest rate-related agreements (1), carrying amount	67,891	71,143
Interest rate-related agreements (1), fair value	67,891	71,143
Foreign currency exchange forwards	1,133	2,079
Foreign currency exchange forwards, Fair value	1,133	2,079
Interest rate lock commitments to originate residential mortgage loans held for sale	6,755	4,571
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	6,755	4,571
Purchased option	4,078	2,854
Purchased option, at fair value	4,078	2,854
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits	13,306,012	12,363,287
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	13,306,012	12,363,287
Brokered CDs and other time deposits	2,347,364	2,727,368
Brokered CDs and other time deposits, Fair value	2,347,364	2,727,368
Short-term funding	1,936,219	2,514,485
Short-term funding, Fair value	1,936,219	2,514,485
Long-term funding	1,176,736	1,177,071
Long-term funding, fair value	1,225,172	1,309,687
Accrued interest payable	6,357	15,931
Accrued interest payable, Fair value	6,357	15,931
Interest rate-related agreements (1)	75,297	80,075
Interest rate-related agreements (1), Fair value	75,297	80,075
Foreign currency exchange forwards	1,066	1,891
Foreign currency exchange forwards, Fair value	1,066	1,891
Standby letters of credit (2), carrying amount	3,583	3,648
Standby letters of credit (2), Fair value	3,583	3,648
Forward commitments to sell residential mortgage loans, fair value	887	4,771
Forward commitments to sell residential mortgage loans	887	4,771
Written option	4,078	2,854
Written option, at fair value	4,078	2,854
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks, Fair Value	360,728	454,958
Interest-bearing deposits in other financial institutions, Fair value	344,148	154,562
Federal funds sold and securities purchased under agreements to resell, Fair value	0	7,075
Investment securities available for sale, at fair value	13,145	12,701
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	0	0
Loans held for sale, fair value	0	0
Loans, net Fair value	0	0
Bank owned life insurance, Fair value	0	0
Accrued interest receivable, Fair value	66,176	68,920
Interest rate-related agreements (1), fair value	0	0
Foreign currency exchange forwards, Fair value	0	0
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	0	0
Purchased option, at fair value	0	0
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	13,306,012	12,363,287
Brokered CDs and other time deposits, Fair value	0	0
Short-term funding, Fair value	0	0
Long-term funding, fair value	0	0
Accrued interest payable, Fair value	6,357	15,931
Interest rate-related agreements (1), Fair value	0	0
Foreign currency exchange forwards, Fair value	0	0
Standby letters of credit (2), Fair value	0	0
Forward commitments to sell residential mortgage loans	0	0
Written option, at fair value	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets
Cash and due from banks, Fair Value	0	0
Interest-bearing deposits in other financial institutions, Fair value	0	0
Federal funds sold and securities purchased under agreements to resell, Fair value	7,100	0
Investment securities available for sale, at fair value	4,655,354	4,923,926
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	177,808	191,188
Loans held for sale, fair value	199,087	255,201
Loans, net Fair value	0	0
Bank owned life insurance, Fair value	546,894	544,764
Accrued interest receivable, Fair value	0	0
Interest rate-related agreements (1), fair value	67,891	71,143
Foreign currency exchange forwards, Fair value	1,133	2,079
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	0	0
Purchased option, at fair value	4,078	2,854
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	0	0
Brokered CDs and other time deposits, Fair value	2,347,364	2,727,368
Short-term funding, Fair value	1,936,219	2,514,485
Long-term funding, fair value	1,225,172	1,309,687
Accrued interest payable, Fair value	0	0
Interest rate-related agreements (1), Fair value	75,297	80,075
Foreign currency exchange forwards, Fair value	1,066	1,891
Standby letters of credit (2), Fair value	3,583	3,648
Forward commitments to sell residential mortgage loans	0	0
Written option, at fair value	4,078	2,854
Fair Value, Inputs, Level 3 [Member]
Financial assets
Cash and due from banks, Fair Value	0	0
Interest-bearing deposits in other financial institutions, Fair value	0	0
Federal funds sold and securities purchased under agreements to resell, Fair value	0	0
Investment securities available for sale, at fair value	601	856
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	0	0
Loans held for sale, fair value	0	0
Loans, net Fair value	13,432,367	12,751,626
Bank owned life insurance, Fair value	0	0
Accrued interest receivable, Fair value	0	0
Interest rate-related agreements (1), fair value	0	0
Foreign currency exchange forwards, Fair value	0	0
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	6,755	4,571
Purchased option, at fair value	0	0
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	0	0
Brokered CDs and other time deposits, Fair value	0	0
Short-term funding, Fair value	0	0
Long-term funding, fair value	0	0
Accrued interest payable, Fair value	0	0
Interest rate-related agreements (1), Fair value	0	0
Foreign currency exchange forwards, Fair value	0	0
Standby letters of credit (2), Fair value	0	0
Forward commitments to sell residential mortgage loans	887	4,771
Written option, at fair value	$ 0	$ 0