Fair Value Accounting (Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 7,309	$ 5,097
Investment securities available for sale	3,603,153	3,587,818
Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	185,151	210,004
Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	876,109	529,597
State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,899	4,434
U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	74,512	43,357
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,422,656	2,630,419
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	8,647	9,672
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,036	19,803
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	86,331	56,102
Private equity investments	0	0
Derivative assets	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	7,309	5,097
Investment securities available for sale	3,515,049	3,529,971
Private equity investments	0	870
Derivative assets	34,743	27,139
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	1,773	1,745
Private equity investments	25,992	27,148
Derivative assets	0	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	7,309	5,097
Mortgage loans held for sale	95,769	59,275
Investment securities available for sale	3,603,153	3,587,818
Private equity investments	25,992	28,018
Mutual funds held in Rabbi Trusts	11,206	10,664
Derivative assets	34,743	27,139
Trading account liabilities	5,666
Derivative liabilities	34,821	27,445
Fair Value, Measurements, Recurring [Member] | US Government Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	2,371
Investment securities available for sale	13,143	13,623
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	2,380	2,922
Investment securities available for sale	185,151	210,004
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,860	1,078
Investment securities available for sale	876,109	529,597
Fair Value, Measurements, Recurring [Member] | State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	698	1,097
Investment securities available for sale	2,899	4,434
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	74,512	43,357
Fair Value, Measurements, Recurring [Member] | Securities Issued By U S Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		126,909
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,422,656	2,630,419
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	8,647	9,672
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,036	19,803
Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	32,336	25,580
Derivative liabilities	32,747	26,030
Fair Value, Measurements, Recurring [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2,407	1,559
Derivative liabilities	659
Fair Value, Measurements, Recurring [Member] | Trading Account Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		1,032
Fair Value, Measurements, Recurring [Member] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	1,415	1,415
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
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	86,331	56,102
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	11,206	10,664
Derivative assets	0	0
Trading account liabilities	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US Government Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
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 [Member] | Level 1 [Member] | Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | State And Municipal Securities [Member]
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 [Member] | Level 1 [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	74,512	43,357
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities Issued By U S Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	8,647	9,672
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,172	3,073
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading Account Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	7,309	5,097
Mortgage loans held for sale	95,769	59,275
Investment securities available for sale	3,515,049	3,529,971
Private equity investments	0	870
Mutual funds held in Rabbi Trusts	0	0
Derivative assets	34,743	27,139
Trading account liabilities	5,666
Derivative liabilities	33,406	26,030
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US Government Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	2,371
Investment securities available for sale	13,143	13,623
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	2,380	2,922
Investment securities available for sale	185,151	210,004
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,860	1,078
Investment securities available for sale	876,109	529,597
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	698	1,097
Investment securities available for sale	2,899	4,434
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities Issued By U S Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		126,909
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	2,422,656	2,630,419
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	15,091	14,985
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	32,336	25,580
Derivative liabilities	32,747	26,030
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2,407	1,559
Derivative liabilities	659
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading Account Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		1,032
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
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	1,773	1,745
Private equity investments	25,992	27,148
Mutual funds held in Rabbi Trusts	0	0
Derivative assets	0	0
Trading account liabilities	0
Derivative liabilities	1,415	1,415
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | US Government Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
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 [Member] | Level 3 [Member] | Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
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 [Member] | Level 3 [Member] | State And Municipal Securities [Member]
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 [Member] | Level 3 [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities Issued By U S Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,773	1,745
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading Account Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading account liabilities		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	$ 1,415	$ 1,415