Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial assets
Interest bearing funds with Federal Reserve Bank	$ 468,148	$ 527,090
Interest earning deposits with banks	6,012	18,720
Federal funds sold and securities purchased under resale agreements	46,847	58,060
Trading account assets	3,045	9,314
Mortgage loans held for sale	61,893	51,545
Investment securities available for sale	3,827,058	3,718,195
Loans, net	24,182,417	23,604,633
Financial liabilities
Non-interest bearing deposits	7,363,476	7,085,804
Federal funds purchased, other short-term borrowings and other short-term liabilities	150,379	159,699
Long-term debt	2,107,245	2,160,881
Level 1
Financial assets
Cash and cash equivalents	377,213	395,175
Interest bearing funds with Federal Reserve Bank	468,148	527,090
Interest earning deposits with banks	6,012	18,720
Federal funds sold and securities purchased under resale agreements	46,847	58,060
Trading account assets	0	1,890
Mortgage loans held for sale	0	0
Other loans held for sale	0
Investment securities available for sale	86,275	114,676
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	12,867	11,479
Loans, net	0	0
GGL/SBA loans servicing asset	0
Derivative assets	0	0
Financial liabilities
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased, other short-term borrowings and other short-term liabilities	150,379	159,699
Long-term debt	0	0
Other liabilities	0	0
Derivative liability positions	0	0
Level 2
Financial assets
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	3,045	7,424
Mortgage loans held for sale	61,893	51,545
Other loans held for sale	127
Investment securities available for sale	3,738,856	3,601,723
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	0	0
Loans, net	0	0
GGL/SBA loans servicing asset	0
Derivative assets	16,725	20,623
Financial liabilities
Non-interest bearing deposits	7,363,476	7,085,804
Interest bearing deposits	17,852,694	17,560,021
Federal funds purchased, other short-term borrowings and other short-term liabilities	0	0
Long-term debt	2,155,543	2,217,544
Other liabilities	0	0
Derivative liability positions	13,389	17,531
Level 3
Financial assets
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	0
Investment securities available for sale	1,927	1,796
Private equity investments	15,698	25,493
Mutual funds held in Rabbi Trusts	0	0
Loans, net	24,191,120	23,709,434
GGL/SBA loans servicing asset	4,297
Derivative assets	0	0
Financial liabilities
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased, other short-term borrowings and other short-term liabilities	0	0
Long-term debt	0	0
Other liabilities	13,941	14,000
Derivative liability positions	5,053	5,768
Carrying Value
Financial assets
Cash and cash equivalents	377,213	395,175
Interest bearing funds with Federal Reserve Bank	468,148	527,090
Interest earning deposits with banks	6,012	18,720
Federal funds sold and securities purchased under resale agreements	46,847	58,060
Trading account assets	3,045	9,314
Mortgage loans held for sale	61,893	51,545
Other loans held for sale	127
Investment securities available for sale	3,827,058	3,718,195
Private equity investments	15,698	25,493
Mutual funds held in Rabbi Trusts	12,867	11,479
Loans, net	24,430,512	23,856,391
GGL/SBA loans servicing asset	4,297
Derivative assets	16,725	20,623
Financial liabilities
Non-interest bearing deposits	7,363,476	7,085,804
Interest bearing deposits	17,855,340	17,562,256
Federal funds purchased, other short-term borrowings and other short-term liabilities	150,379	159,699
Long-term debt	2,107,245	2,160,881
Other liabilities	13,941	14,000
Derivative liability positions	18,442	23,299
Fair Value
Financial assets
Cash and cash equivalents	377,213	395,175
Interest bearing funds with Federal Reserve Bank	468,148	527,090
Interest earning deposits with banks	6,012	18,720
Federal funds sold and securities purchased under resale agreements	46,847	58,060
Trading account assets	3,045	9,314
Mortgage loans held for sale	61,893	51,545
Other loans held for sale	127
Investment securities available for sale	3,827,058	3,718,195
Private equity investments	15,698	25,493
Mutual funds held in Rabbi Trusts	12,867	11,479
Loans, net	24,191,120	23,709,434
GGL/SBA loans servicing asset	4,297
Derivative assets	16,725	20,623
Financial liabilities
Non-interest bearing deposits	7,363,476	7,085,804
Interest bearing deposits	17,852,694	17,560,021
Federal funds purchased, other short-term borrowings and other short-term liabilities	150,379	159,699
Long-term debt	2,155,543	2,217,544
Other liabilities	13,941	14,000
Derivative liability positions	$ 18,442	$ 23,299