Fair Value Accounting (Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 1,778	$ 9,314
Investment securities available for sale	3,782,942	3,718,195
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	166,279	174,202
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	696,892	890,442
State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,801	2,794
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,104	19,840
U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	82,891	107,802
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	2,802,544	2,506,340
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		3,782
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	1,890
Investment securities available for sale	85,999	114,676
Private equity investments	0	0
Derivative assets	0	0
Other liabilities	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,778	7,424
Investment securities available for sale	3,695,092	3,601,723
Private equity investments	0	0
Derivative assets	17,791	20,623
Other liabilities	0	0
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities available for sale	1,851	1,796
Private equity investments	23,679	25,493
GGL/SBA loans servicing asset	4,178
Derivative assets	0	0
Other liabilities	11,421	14,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,778	9,314
Mortgage loans held for sale	57,686	51,545
Investment securities available for sale	3,782,942	3,718,195
Private equity investments	23,679	25,493
Mutual funds held in Rabbi Trusts	12,431	11,479
GGL/SBA loans servicing asset	4,178
Derivative assets	17,791	20,623
Trading account liabilities	1,000
Other liabilities	11,421	14,000
Derivative liabilities	21,896	23,299
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		1,990
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	980	3,460
Investment securities available for sale	166,279	174,202
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	455	3,438
Investment securities available for sale	696,892	890,442
Fair Value, Measurements, Recurring [Member] | State And Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	343	426
Investment securities available for sale	1,801	2,794
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	20,104	19,840
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	82,891	107,802
Fair Value, Measurements, Recurring [Member] | US Government Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	12,431	12,993
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	2,802,544	2,506,340
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale		3,782
Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	15,548	17,157
Derivative liabilities	15,923	17,531
Fair Value, Measurements, Recurring [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2,243	3,466
Derivative liabilities	561
Fair Value, Measurements, Recurring [Member] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	5,412	5,768
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	1,890
Mortgage loans held for sale	0	0
Investment securities available for sale	85,999	114,676
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	12,431	11,479
GGL/SBA loans servicing asset	0
Derivative assets	0	0
Trading account liabilities	0
Other liabilities	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		1,890
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	3,108	3,092
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	82,891	107,802
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 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		3,782
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] | 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	1,778	7,424
Mortgage loans held for sale	57,686	51,545
Investment securities available for sale	3,695,092	3,601,723
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	0	0
GGL/SBA loans servicing asset	0
Derivative assets	17,791	20,623
Trading account liabilities	1,000
Other liabilities	0	0
Derivative liabilities	16,484	17,531
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		100
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	980	3,460
Investment securities available for sale	166,279	174,202
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	455	3,438
Investment securities available for sale	696,892	890,442
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	343	426
Investment securities available for sale	1,801	2,794
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	15,145	14,952
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 Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	12,431	12,993
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	2,802,544	2,506,340
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
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest Rate Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	15,548	17,157
Derivative liabilities	15,923	17,531
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Mortgage Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2,243	3,466
Derivative liabilities	561
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	1,851	1,796
Private equity investments	23,679	25,493
Mutual funds held in Rabbi Trusts	0	0
GGL/SBA loans servicing asset	4,178
Derivative assets	0	0
Trading account liabilities	0
Other liabilities	11,421	14,000
Derivative liabilities	5,412	5,768
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		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] | Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities available for sale	1,851	1,796
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 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 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
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] | Visa Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	$ 5,412	$ 5,768