Fair Value Accounting (Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 1,001	$ 5,097
Investment securities available for sale	3,580,359	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	192,783	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	635,614	529,597
State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,046	4,434
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,127	19,803
U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	74,823	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	2,581,669	2,630,419
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	8,731	9,672
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0
Investment securities available for sale	86,723	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	1,001	5,097
Investment securities available for sale	3,492,011	3,529,971
Private equity investments	658	870
Derivative assets	39,345	27,139
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	1,625	1,745
Private equity investments	26,866	27,148
Derivative assets	0	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,001	5,097
Mortgage loans held for sale	87,824	59,275
Investment securities available for sale	3,580,359	3,587,818
Private equity investments	27,524	28,018
Mutual funds held in Rabbi Trusts	11,141	10,664
Derivative assets	39,345	27,139
Trading account liabilities	789
Derivative liabilities	40,103	27,445
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	798	2,922
Investment securities available for sale	192,783	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	11	1,078
Investment securities available for sale	635,614	529,597
Fair Value, Measurements, Recurring [Member] | Other US Government Agencies Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	177
Fair Value, Measurements, Recurring [Member] | State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	15	1,097
Investment securities available for sale	3,046	4,434
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,127	19,803
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	74,823	43,357
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	13,449	13,623
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	50,117	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	2,581,669	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	8,731	9,672
Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	36,804	25,580
Derivative liabilities	37,221	26,030
Fair Value, Measurements, Recurring [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2,541	1,559
Derivative liabilities	1,467
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	86,723	56,102
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	11,141	10,664
Derivative assets	0	0
Trading account liabilities	0
Derivative liabilities	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] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	3,169	3,073
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	74,823	43,357
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US Government Agencies Debt 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] | 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	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	8,731	9,672
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	1,001	5,097
Mortgage loans held for sale	87,824	59,275
Investment securities available for sale	3,492,011	3,529,971
Private equity investments	658	870
Mutual funds held in Rabbi Trusts	0	0
Derivative assets	39,345	27,139
Trading account liabilities	789
Derivative liabilities	38,688	26,030
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	798	2,922
Investment securities available for sale	192,783	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	11	1,078
Investment securities available for sale	635,614	529,597
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other US Government Agencies Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	177
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	15	1,097
Investment securities available for sale	3,046	4,434
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	15,333	14,985
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] | US Government Agencies Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	13,449	13,623
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	50,117	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	2,581,669	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] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	36,804	25,580
Derivative liabilities	37,221	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	2,541	1,559
Derivative liabilities	1,467
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	1,625	1,745
Private equity investments	26,866	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] | 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] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,625	1,745
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] | US Government Agencies Debt 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	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] | 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