Fair Value Accounting (Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 26,251
Investment securities available for sale	3,990,978	$ 3,987,069
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,065,041	1,111,999
State and municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	115	180
Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	17,126	20,391
U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	120,931	82,674
Mortgage-backed securities issued by U.S. Government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	112,868	120,440
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,664,000	2,640,523
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	522
Investment securities available for sale	120,931	85,836
Private equity investments	0	0
GGL/SBA loans servicing asset	0	0
Derivative assets	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,251	3,298
Investment securities available for sale	3,868,195	3,899,298
Private equity investments	0	0
GGL/SBA loans servicing asset	0	0
Derivative assets	9,407	11,722
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	1,852	1,935
Private equity investments	12,715	15,771
GGL/SBA loans servicing asset	3,971	4,101
Derivative assets	0	0
Fair Value, Measurements, Recurring Basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		3,820
Mortgage loans held for sale	50,439	48,024
Investment securities available for sale	3,990,978	3,987,069
Private equity investments	12,715	15,771
Mutual funds held in Rabbi Trusts	13,385	14,140
GGL/SBA loans servicing asset	3,971	4,101
Derivative assets	9,407	11,722
Trading account liabilities	23,856
Earnout liability	11,348	11,348
Derivative liabilities	20,096	17,097
Fair Value, Measurements, Recurring Basis | Mortgages
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		1,000
Fair Value, Measurements, Recurring Basis | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities		129
Fair Value, Measurements, Recurring Basis | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		522
Fair Value, Measurements, Recurring Basis | U.S. Government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	25,971
Investment securities available for sale	10,897	10,862
Fair Value, Measurements, Recurring Basis | Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	240	296
Investment securities available for sale	1,065,041	1,111,999
Fair Value, Measurements, Recurring Basis | State and municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	40
Investment securities available for sale	115	180
Fair Value, Measurements, Recurring Basis | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	17,126	20,391
Fair Value, Measurements, Recurring Basis | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	120,931	82,674
Fair Value, Measurements, Recurring Basis | Mortgage-backed securities issued by U.S. Government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		3,002
Investment securities available for sale	112,868	120,440
Fair Value, Measurements, Recurring Basis | Mortgage-backed securities issued by U.S. Government sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,664,000	2,640,523
Fair Value, Measurements, Recurring Basis | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,131
Fair Value, Measurements, Recurring Basis | Interest rate contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7,672	10,786
Derivative liabilities	16,122	12,638
Fair Value, Measurements, Recurring Basis | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1,735	936
Fair Value, Measurements, Recurring Basis | Visa derivative
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	3,974	4,330
Fair Value, Measurements, Recurring Basis | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	522
Mortgage loans held for sale	0	0
Investment securities available for sale	120,931	85,836
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	13,385	14,140
GGL/SBA loans servicing asset	0	0
Derivative assets	0	0
Trading account liabilities	0
Earnout liability	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgages
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities		0
Fair Value, Measurements, Recurring Basis | Level 1 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		522
Fair Value, Measurements, Recurring Basis | Level 1 | U.S. Government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale		0
Fair Value, Measurements, Recurring Basis | Level 1 | Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | State and municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	3,162
Fair Value, Measurements, Recurring Basis | Level 1 | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	120,931	82,674
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage-backed securities issued by U.S. Government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage-backed securities issued by U.S. Government sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,131
Fair Value, Measurements, Recurring Basis | Level 1 | Interest rate contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Fair Value, Measurements, Recurring Basis | Level 1 | Visa derivative
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,251	3,298
Mortgage loans held for sale	50,439	48,024
Investment securities available for sale	3,868,195	3,899,298
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	0	0
GGL/SBA loans servicing asset	0	0
Derivative assets	9,407	11,722
Trading account liabilities	23,856
Earnout liability	0	0
Derivative liabilities	16,122	12,767
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgages
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		1,000
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities		129
Fair Value, Measurements, Recurring Basis | Level 2 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Fair Value, Measurements, Recurring Basis | Level 2 | U.S. Government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	25,971
Investment securities available for sale		10,862
Fair Value, Measurements, Recurring Basis | Level 2 | Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	240	296
Investment securities available for sale	1,065,041	1,111,999
Fair Value, Measurements, Recurring Basis | Level 2 | State and municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	40
Investment securities available for sale	115	180
Fair Value, Measurements, Recurring Basis | Level 2 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	15,274	15,294
Fair Value, Measurements, Recurring Basis | Level 2 | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage-backed securities issued by U.S. Government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		3,002
Investment securities available for sale	112,868	120,440
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage-backed securities issued by U.S. Government sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,664,000	2,640,523
Fair Value, Measurements, Recurring Basis | Level 2 | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0
Fair Value, Measurements, Recurring Basis | Level 2 | Interest rate contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7,672	10,786
Derivative liabilities	16,122	12,638
Fair Value, Measurements, Recurring Basis | Level 2 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1,735	936
Fair Value, Measurements, Recurring Basis | Level 2 | Visa derivative
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Mortgage loans held for sale	0	0
Investment securities available for sale	1,852	1,935
Private equity investments	12,715	15,771
Mutual funds held in Rabbi Trusts	0	0
GGL/SBA loans servicing asset	3,971	4,101
Derivative assets	0	0
Trading account liabilities	0
Earnout liability	11,348	11,348
Derivative liabilities	3,974	4,330
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgages
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities		0
Fair Value, Measurements, Recurring Basis | Level 3 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Fair Value, Measurements, Recurring Basis | Level 3 | U.S. Government agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | State and municipal securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,852	1,935
Fair Value, Measurements, Recurring Basis | Level 3 | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage-backed securities issued by U.S. Government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage-backed securities issued by U.S. Government sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0
Fair Value, Measurements, Recurring Basis | Level 3 | Interest rate contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Mortgage derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Fair Value, Measurements, Recurring Basis | Level 3 | Visa derivative
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	$ 3,974	$ 4,330