Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 428,487	$ 614,630
Interest bearing funds with Federal Reserve Bank	1,459,251	1,498,390
Interest earning deposits with banks	22,065	23,442
Federal funds sold and securities purchased under resale agreements	88,636	113,517
Trading account assets	23,069	11,102
Mortgage loans held for sale	112,761	212,663
Other loans held for sale	12,083	10,690
Investment securities available for sale	3,077,706	2,981,112	2,981,112
Loans, net	19,273,403	19,168,285
Non-interest bearing deposits	5,203,437	5,665,527
Federal funds purchased and other short-term borrowings	222,933	201,243
Long-term debt	1,885,689	1,726,455
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	428,487	614,630
Interest bearing funds with Federal Reserve Bank	1,459,251	1,498,390
Interest earning deposits with banks	22,065	23,442
Federal funds sold and securities purchased under resale agreements	88,636	113,517
Trading account assets	0	0
Mortgage loans held for sale	0	0
Other loans held for sale	0	0
Investment securities available for sale	4,418	3,205
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	10,460	10,001
Loans, net	0	0
Derivative asset positions	0	0
Trading account liabilities	0	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and other short-term borrowings	222,933	201,243
Salary stock units	793	1,888
Long-term debt	0	0
Derivative liability positions	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing funds with Federal Reserve Bank	0	0
Interest earning deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Trading account assets	23,069	11,102
Mortgage loans held for sale	112,761	212,663
Other loans held for sale	0	0
Investment securities available for sale	3,069,834	2,974,729
Private equity investments	1,345	1,168
Mutual funds held in Rabbi Trusts	0	0
Loans, net	0	0
Derivative asset positions	52,000	64,662
Trading account liabilities	15,847	91
Non-interest bearing deposits	5,203,437	5,665,527
Interest bearing deposits	15,517,284	15,415,160
Federal funds purchased and other short-term borrowings	0	0
Salary stock units	0	0
Long-term debt	1,937,232	1,784,223
Derivative liability positions	45,991	63,437
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing funds with Federal Reserve Bank	0	0
Interest earning deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Trading account assets	0	0
Mortgage loans held for sale	0	0
Other loans held for sale	12,083	10,690
Investment securities available for sale	3,454	3,178
Private equity investments	29,568	30,708
Mutual funds held in Rabbi Trusts	0	0
Loans, net	19,312,409	19,254,199
Derivative asset positions	0	0
Trading account liabilities	0	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and other short-term borrowings	0	0
Salary stock units	0	0
Long-term debt	0	0
Derivative liability positions	2,977	2,956
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	428,487	614,630
Interest bearing funds with Federal Reserve Bank	1,459,251	1,498,390
Interest earning deposits with banks	22,065	23,442
Federal funds sold and securities purchased under resale agreements	88,636	113,517
Trading account assets	23,069	11,102
Mortgage loans held for sale	112,761	212,663
Other loans held for sale	12,083	10,690
Investment securities available for sale	3,077,706	2,981,112
Private equity investments	30,913	31,876
Mutual funds held in Rabbi Trusts	10,460	10,001
Loans, net	19,608,283	19,541,690
Derivative asset positions	52,000	64,662
Trading account liabilities	15,847	91
Non-interest bearing deposits	5,203,437	5,665,527
Interest bearing deposits	15,507,266	15,391,517
Federal funds purchased and other short-term borrowings	222,933	201,243
Salary stock units	793	1,888
Long-term debt	1,885,689	1,726,455
Derivative liability positions	48,968	66,393
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	428,487	614,630
Interest bearing funds with Federal Reserve Bank	1,459,251	1,498,390
Interest earning deposits with banks	22,065	23,442
Federal funds sold and securities purchased under resale agreements	88,636	113,517
Trading account assets	23,069	11,102
Mortgage loans held for sale	112,761	212,663
Other loans held for sale	12,083	10,690
Investment securities available for sale	3,077,706	2,981,112
Private equity investments	30,913	31,876
Mutual funds held in Rabbi Trusts	10,460	10,001
Loans, net	19,312,409	19,254,199
Derivative asset positions	52,000	64,662
Trading account liabilities	15,847	91
Non-interest bearing deposits	5,203,437	5,665,527
Interest bearing deposits	15,517,284	15,415,160
Federal funds purchased and other short-term borrowings	222,933	201,243
Salary stock units	793	1,888
Long-term debt	1,937,232	1,784,223
Derivative liability positions	$ 48,968	$ 66,393