Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Financial assets
Cash and due from banks	$ 563,304		$ 454,958
Cash and due from banks, Fair Value	563,304		454,958
Interest-bearing deposits in other financial institutions	147,434		154,562
Interest-bearing deposits in other financial institutions, Fair value	147,434		154,562
Federal funds sold and securities purchased under agreements to resell	27,135		7,075
Federal funds sold and securities purchased under agreements to resell, Fair value	27,135		7,075
Investment securities held to maturity, carrying amount	39,877		0
Investment securities held to maturity, fair value	39,679		0
Investment securities available for sale, at fair value	4,926,758		4,937,483
Investment securities available for sale, at fair value	4,926,758		4,937,483
Federal Home Loan Bank and Federal Reserve Bank stocks, carrying amount	166,774		191,188
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	166,774		191,188
Loans held for sale	261,410		249,195
Loans held for sale, fair value	265,914		255,201
Loans, net	15,113,613		13,652,920
Loans, net Fair value	14,873,851		12,751,626
Bank owned life insurance, carrying amount	556,556		544,764
Bank owned life insurance, Fair value	556,556		544,764
Accrued interest receivable, carrying amount	68,386		68,920
Accrued interest receivable, Fair value	68,386		68,920
Interest rate-related agreements (1), carrying amount	69,370	[1]	71,143	[1]
Fair value	69,370	[1]	71,143	[1]
Foreign currency exchange forwards	1,341		2,079
Foreign currency exchange forwards, Fair value	1,341		2,079
Interest rate lock commitments to originate residential mortgage loans held for sale	7,794		4,571
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	7,794		4,571
Purchased option	3,620		2,854
Purchased option, at fair value	3,620		2,854
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits	14,941,971		12,363,287
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	14,941,971		12,363,287
Brokered CDs and other time deposits	1,997,894		2,727,368
Brokered CDs and other time deposits, Fair value	1,997,894		2,727,368
Short-term funding	2,326,939		2,514,485
Short-term funding, Fair value	2,326,939		2,514,485
Long-term funding	1,015,346		1,177,071
Long-term funding, fair value	1,041,550		1,309,687
Accrued interest payable	10,208		15,931
Accrued interest payable, Fair value	10,208		15,931
Interest rate-related agreements (1)	75,131	[1]	80,075	[1]
Interest rate-related agreements (1), Fair value	75,131	[1]	80,075	[1]
Foreign currency exchange forwards	1,212		1,891
Foreign currency exchange forwards, Fair value	1,212		1,891
Standby letters of credit (2), carrying amount	3,811	[2]	3,648	[2]
Standby letters of credit (2), Fair value	3,811	[2]	3,648	[2]
Forward commitments to sell residential mortgage loans	147		4,771
Forward commitments to sell residential mortgage loans, fair value	147		4,771
Written option	3,620		2,854
Written option, at fair value	3,620		2,854
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks, Fair Value	563,304		454,958
Interest-bearing deposits in other financial institutions, Fair value	147,434		154,562
Federal funds sold and securities purchased under agreements to resell, Fair value	27,135		7,075
Investment securities held to maturity, fair value	0		0
Investment securities available for sale, at fair value	3,845		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	68,386		68,920
Fair value	0	[1]	0	[1]
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	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	10,208		15,931
Interest rate-related agreements (1), Fair value	0	[1]	0	[1]
Foreign currency exchange forwards, Fair value	0		0
Standby letters of credit (2), Fair value	0	[2]	0	[2]
Forward commitments to sell residential mortgage loans, fair value	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	0		0
Investment securities held to maturity, fair value	39,679		0
Investment securities available for sale, at fair value	4,922,433		4,923,926
Federal Home Loan Bank and Federal Reserve Bank stocks, Fair value	166,774		191,188
Loans held for sale, fair value	265,914		255,201
Loans, net Fair value	0		0
Bank owned life insurance, Fair value	556,556		544,764
Accrued interest receivable, Fair value	0		0
Fair value	69,370	[1]	71,143	[1]
Foreign currency exchange forwards, Fair value	1,341		2,079
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	0		0
Purchased option, at fair value	3,620		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	1,997,894		2,727,368
Short-term funding, Fair value	2,326,939		2,514,485
Long-term funding, fair value	1,041,550		1,309,687
Accrued interest payable, Fair value	0		0
Interest rate-related agreements (1), Fair value	75,131	[1]	80,075	[1]
Foreign currency exchange forwards, Fair value	1,212		1,891
Standby letters of credit (2), Fair value	3,811	[2]	3,648	[2]
Forward commitments to sell residential mortgage loans, fair value	0		0
Written option, at fair value	3,620		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 held to maturity, fair value	0		0
Investment securities available for sale, at fair value	480		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	14,873,851		12,751,626
Bank owned life insurance, Fair value	0		0
Accrued interest receivable, Fair value	0		0
Fair value	0	[1]	0	[1]
Foreign currency exchange forwards, Fair value	0		0
Interest rate lock commitments to originate residential mortgage loans held for sale, fair value	7,794		4,571
Purchased option, at fair value	0		0
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market deposits, Fair value	14,941,971		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	0		0
Interest rate-related agreements (1), Fair value	0	[1]	0	[1]
Foreign currency exchange forwards, Fair value	0		0
Standby letters of credit (2), Fair value	0	[2]	0	[2]
Forward commitments to sell residential mortgage loans, fair value	147		4,771
Written option, at fair value	$ 0		$ 0

[1] (1) At December 31, 2012 and 2011, the notional amount of cash flow hedge interest rate swap agreements was $0 million and $100 million, respectively. See Note 14 for information on the fair value of derivative financial instruments.

[2] (2) The commitment on standby letters of credit was $304 million and $320 million at December 31, 2012 and 2011, respectively. See Note 13 for additional information on the standby letters of credit and for information on the fair value of lending-related commitments.