Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 523,302	$ 510,423
Interest bearing funds with Federal Reserve Bank	1,301,244	1,567,006
Interest earning deposits with banks	16,003	13,590
Federal funds sold and securities purchased under resale agreements	118,098	158,916
Trading account assets	12,331	16,866
Mortgage loans held for sale	120,007	161,509
Other loans held for sale	32,601	30,156
Investment securities available for sale	3,570,346	3,690,125
Loans, net	19,226,802	19,543,319
Non-interest bearing deposits	5,607,680	5,366,868
Federal funds purchased and other short-term borrowings	351,173	313,757
Long-term debt	1,301,616	1,364,727
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	523,302
Interest bearing funds with Federal Reserve Bank	1,301,244
Interest earning deposits with banks	16,003
Federal funds sold and securities purchased under resale agreements	118,098
Trading account assets	0
Mortgage loans held for sale	0
Other loans held for sale	0
Investment securities available for sale	3,102
Private equity investments	0
Loans, net	0
Derivative asset positions	0
Trading account liabilities	0
Non-interest bearing deposits	0
Interest bearing deposits	0
Federal funds purchased and other short-term borrowings	351,173
Long-term debt	0
Derivative liability positions	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0
Interest bearing funds with Federal Reserve Bank	0
Interest earning deposits with banks	0
Federal funds sold and securities purchased under resale agreements	0
Trading account assets	12,331
Mortgage loans held for sale	120,007
Other loans held for sale	0
Investment securities available for sale	3,562,141
Private equity investments	861
Loans, net	0
Derivative asset positions	78,358
Trading account liabilities	766
Non-interest bearing deposits	5,607,680
Interest bearing deposits	15,991,415
Federal funds purchased and other short-term borrowings	0
Long-term debt	1,308,580
Derivative liability positions	77,856
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0
Interest bearing funds with Federal Reserve Bank	0
Interest earning deposits with banks	0
Federal funds sold and securities purchased under resale agreements	0
Trading account assets	0
Mortgage loans held for sale	0
Other loans held for sale	32,601
Investment securities available for sale	5,103
Private equity investments	29,847
Loans, net	19,291,650
Derivative asset positions	0
Trading account liabilities	0
Non-interest bearing deposits	0
Interest bearing deposits	0
Federal funds purchased and other short-term borrowings	0
Long-term debt	0
Derivative liability positions	3,050
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	523,302	510,423
Interest bearing funds with Federal Reserve Bank	1,301,244	1,567,006
Interest earning deposits with banks	16,003	13,590
Federal funds sold and securities purchased under resale agreements	118,098	158,916
Trading account assets	12,331	16,866
Mortgage loans held for sale	120,007	161,509
Other loans held for sale	32,601	30,156
Investment securities available for sale	3,570,346	3,690,125
Private equity investments	30,708	22,015
Loans, net	19,226,802	19,543,319
Derivative asset positions	78,358	84,923
Trading account liabilities	766
Non-interest bearing deposits	5,607,680	5,366,868
Interest bearing deposits	15,957,385	17,044,884
Federal funds purchased and other short-term borrowings	351,173	313,757
Long-term debt	1,301,616	1,364,727
Derivative liability positions	80,906	96,574
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	523,302	510,423
Interest bearing funds with Federal Reserve Bank	1,301,244	1,567,006
Interest earning deposits with banks	16,003	13,590
Federal funds sold and securities purchased under resale agreements	118,098	158,916
Trading account assets	12,331	16,866
Mortgage loans held for sale	120,007	161,509
Other loans held for sale	32,601	30,156
Investment securities available for sale	3,570,346	3,690,125
Private equity investments	30,708	22,015
Loans, net	19,291,650	19,621,279
Derivative asset positions	78,358	84,923
Trading account liabilities	766
Non-interest bearing deposits	5,607,680	5,366,868
Interest bearing deposits	15,991,415	17,092,784
Federal funds purchased and other short-term borrowings	351,173	313,757
Long-term debt	1,308,580	1,302,560
Derivative liability positions	$ 80,906	$ 96,574