Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Assets
Cash and cash equivalents	$ 397,848	$ 395,175
Interest bearing funds with Federal Reserve Bank	460,928	527,090
Interest earning deposits with banks	26,311	18,720
Federal funds sold and securities purchased under resale agreements	47,846	58,060
Trading account assets	3,820	9,314
Mortgage loans held for sale	48,024	51,545
Other loans held for sale	11,356	0
Investment securities available for sale	3,987,069	3,718,195
Private equity investments	15,771	25,493
Loans, net of deferred fees and costs	24,538,196	23,604,633
Derivative assets	11,722	20,623
Financial Liabilities
Non-interest bearing deposits	7,686,339	7,085,804
Interest bearing deposits	18,461,561	17,562,256
Federal funds purchased and securities sold under repurchase agreements	161,190	159,699	$ 177,025
Long-term debt	1,706,138	2,160,881
Level 1
Financial Assets
Cash and cash equivalents	397,848	395,175
Interest bearing funds with Federal Reserve Bank	460,928	527,090
Interest earning deposits with banks	26,311	18,720
Federal funds sold and securities purchased under resale agreements	47,846	58,060
Trading account assets	522	1,890
Mortgage loans held for sale	0	0
Other loans held for sale	0
Investment securities available for sale	85,836	114,676
Private equity investments	0	0
Mutual funds held in rabbi trusts	14,140	11,479
Loans, net of deferred fees and costs	0	0
GGL/SBA loans servicing asset	0
Derivative assets	0	0
Financial Liabilities
Trading account liabilities	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	161,190	159,699
Long-term debt	0	0
Earnout Liabilities, Fair Value Disclosure	0	0
Derivative liabilities	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	3,298	7,424
Mortgage loans held for sale	48,024	51,545
Other loans held for sale	0
Investment securities available for sale	3,899,298	3,601,723
Private equity investments	0	0
Mutual funds held in rabbi trusts	0	0
Loans, net of deferred fees and costs	0	0
GGL/SBA loans servicing asset	0
Derivative assets	11,722	20,623
Financial Liabilities
Trading account liabilities	1,000
Non-interest bearing deposits	7,686,339	7,085,804
Interest bearing deposits	18,465,475	17,560,021
Federal funds purchased and securities sold under repurchase agreements	0	0
Long-term debt	1,721,814	2,217,544
Earnout Liabilities, Fair Value Disclosure	0	0
Derivative liabilities	12,767	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	11,356
Investment securities available for sale	1,935	1,796
Private equity investments	15,771	25,493
Mutual funds held in rabbi trusts	0	0
Loans, net of deferred fees and costs	24,507,141	23,709,434
GGL/SBA loans servicing asset	4,101
Derivative assets	0	0
Financial Liabilities
Trading account liabilities	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	0	0
Long-term debt	0	0
Earnout Liabilities, Fair Value Disclosure	11,348	14,000
Derivative liabilities	4,330	5,768
Carrying Value
Financial Assets
Cash and cash equivalents	397,848	395,175
Interest bearing funds with Federal Reserve Bank	460,928	527,090
Interest earning deposits with banks	26,311	18,720
Federal funds sold and securities purchased under resale agreements	47,846	58,060
Trading account assets	3,820	9,314
Mortgage loans held for sale	48,024	51,545
Other loans held for sale	11,356
Investment securities available for sale	3,987,069	3,718,195
Private equity investments	15,771	25,493
Mutual funds held in rabbi trusts	14,140	11,479
Loans, net of deferred fees and costs	24,787,464	23,856,391
GGL/SBA loans servicing asset	4,101
Derivative assets	11,722	20,623
Financial Liabilities
Trading account liabilities	1,000
Non-interest bearing deposits	7,686,339	7,085,804
Interest bearing deposits	18,461,561	17,562,256
Federal funds purchased and securities sold under repurchase agreements	161,190	159,699
Long-term debt	1,706,138	2,160,881
Earnout Liabilities, Fair Value Disclosure	11,348	14,000
Derivative liabilities	17,097	23,299
Estimated Fair Value
Financial Assets
Cash and cash equivalents	397,848	395,175
Interest bearing funds with Federal Reserve Bank	460,928	527,090
Interest earning deposits with banks	26,311	18,720
Federal funds sold and securities purchased under resale agreements	47,846	58,060
Trading account assets	3,820	9,314
Mortgage loans held for sale	48,024	51,545
Other loans held for sale	11,356
Investment securities available for sale	3,987,069	3,718,195
Private equity investments	15,771	25,493
Mutual funds held in rabbi trusts	14,140	11,479
Loans, net of deferred fees and costs	24,507,141	23,709,434
GGL/SBA loans servicing asset	4,101
Derivative assets	11,722	20,623
Financial Liabilities
Trading account liabilities	1,000
Non-interest bearing deposits	7,686,339	7,085,804
Interest bearing deposits	18,465,475	17,560,021
Federal funds purchased and securities sold under repurchase agreements	161,190	159,699
Long-term debt	1,721,814	2,217,544
Earnout Liabilities, Fair Value Disclosure	11,348	14,000
Derivative liabilities	$ 17,097	$ 23,299