Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 824,971	$ 860,016
Securities Available-for-Sale, Less than 12 months, Unrealized losses	10,963	11,778
Securities Available-for-Sale, 12 months or longer, Fair value	46,178	47,163
Securities Available-for-Sale, 12 months or longer, Unrealized losses	409	531
Securities Available-for-Sale, Fair value, Total	871,149	907,179
Securities Available-for-Sale, Unrealized losses, Total	11,372	12,309
Securities Held-to-Maturity, Less than 12 months, Fair value	118,439	134,909
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	3,945	5,148
Securities Held-to-Maturity, 12 months or longer, Fair value	7,509	7,564
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	77	87
Securities Held-to-Maturity, Fair value, Total	125,948	142,473
Securities Held-to-Maturity, Unrealized losses, Total	4,022	5,235
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	248,525	247,695
Securities Available-for-Sale, Less than 12 months, Unrealized losses	1,475	2,305
Securities Available-for-Sale, 12 months or longer, Fair value	19,896	19,838
Securities Available-for-Sale, 12 months or longer, Unrealized losses	104	162
Securities Available-for-Sale, Fair value, Total	268,421	267,533
Securities Available-for-Sale, Unrealized losses, Total	1,579	2,467
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	576,446	612,321
Securities Available-for-Sale, Less than 12 months, Unrealized losses	9,488	9,473
Securities Available-for-Sale, 12 months or longer, Fair value	26,282	27,325
Securities Available-for-Sale, 12 months or longer, Unrealized losses	305	369
Securities Available-for-Sale, Fair value, Total	602,728	639,646
Securities Available-for-Sale, Unrealized losses, Total	9,793	9,842
Securities Held-to-Maturity, 12 months or longer, Fair value	7,509	7,564
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	77	87
Securities Held-to-Maturity, Fair value, Total	7,509	7,564
Securities Held-to-Maturity, Unrealized losses, Total	77	87
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Less than 12 months, Fair value	118,439	134,909
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	3,945	5,148
Securities Held-to-Maturity, 12 months or longer, Fair value	0
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	0
Securities Held-to-Maturity, Fair value, Total	118,439	134,909
Securities Held-to-Maturity, Unrealized losses, Total	$ 3,945	$ 5,148

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

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