Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 386,402	$ 469,630
Interest bearing funds with Federal Reserve Bank	750,446	644,528
Interest earning deposits with banks	13,612	24,325
Federal funds sold and securities purchased under resale agreements	70,918	80,975
Trading account assets	12,705	6,113
Mortgage loans held for sale	72,333	45,384
Other loans held for sale	338	10,685
Investment securities available for sale	3,050,257	3,199,358
Loans, net	20,319,190	19,750,238
Non-interest bearing deposits	5,813,809	5,642,751
Federal funds purchased and securities sold under repurchase agreements	107,160	148,132
Long-term debt	2,130,934	2,033,141
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	386,402	469,630
Interest bearing funds with Federal Reserve Bank	750,446	644,528
Interest earning deposits with banks	13,612	24,325
Federal funds sold and securities purchased under resale agreements	70,918	80,975
Trading account assets	97	0
Mortgage loans held for sale	0	0
Other loans held for sale	0	0
Investment securities available for sale	51,031	26,716
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	10,817	11,246
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 securities sold under repurchase agreements	107,160	148,132
Salary stock units	728	1,764
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	12,608	6,113
Mortgage loans held for sale	72,333	45,384
Other loans held for sale	0	0
Investment securities available for sale	2,997,441	3,170,292
Private equity investments	1,094	1,615
Mutual funds held in Rabbi Trusts	0	0
Loans, net	0	0
Derivative asset positions	31,322	40,004
Trading account liabilities	6,264	1,763
Non-interest bearing deposits	5,813,809	5,642,751
Interest bearing deposits	15,177,126	15,244,020
Federal funds purchased and securities sold under repurchase agreements	0	0
Salary stock units	0	0
Long-term debt	2,185,455	2,095,720
Derivative liability positions	31,009	39,436
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	338	10,685
Investment securities available for sale	1,785	2,350
Private equity investments	27,232	27,745
Mutual funds held in Rabbi Trusts	0	0
Loans, net	20,334,382	19,763,708
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 securities sold under repurchase agreements	0	0
Salary stock units	0	0
Long-term debt	0	0
Derivative liability positions	4,021	2,706
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	386,402	469,630
Interest bearing funds with Federal Reserve Bank	750,446	644,528
Interest earning deposits with banks	13,612	24,325
Federal funds sold and securities purchased under resale agreements	70,918	80,975
Trading account assets	12,705	6,113
Mortgage loans held for sale	72,333	45,384
Other loans held for sale	338	10,685
Investment securities available for sale	3,050,257	3,199,358
Private equity investments	28,326	29,360
Mutual funds held in Rabbi Trusts	10,817	11,246
Loans, net	20,588,566	20,057,798
Derivative asset positions	31,322	40,004
Trading account liabilities	6,264	1,763
Non-interest bearing deposits	5,813,809	5,642,751
Interest bearing deposits	15,175,972	15,234,039
Federal funds purchased and securities sold under repurchase agreements	107,160	148,132
Salary stock units	728	1,764
Long-term debt	2,130,934	2,033,141
Derivative liability positions	35,030	42,142
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	386,402	469,630
Interest bearing funds with Federal Reserve Bank	750,446	644,528
Interest earning deposits with banks	13,612	24,325
Federal funds sold and securities purchased under resale agreements	70,918	80,975
Trading account assets	12,705	6,113
Mortgage loans held for sale	72,333	45,384
Other loans held for sale	338	10,685
Investment securities available for sale	3,050,257	3,199,358
Private equity investments	28,326	29,360
Mutual funds held in Rabbi Trusts	10,817	11,246
Loans, net	20,334,382	19,763,708
Derivative asset positions	31,322	40,004
Trading account liabilities	6,264	1,763
Non-interest bearing deposits	5,813,809	5,642,751
Interest bearing deposits	15,177,126	15,244,020
Federal funds purchased and securities sold under repurchase agreements	107,160	148,132
Salary stock units	728	1,764
Long-term debt	2,185,455	2,095,720
Derivative liability positions	$ 35,030	$ 42,142