Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 544,951	$ 860,016
Securities Available-for-Sale, Less than 12 months, Unrealized losses	4,848	11,778
Securities Available-for-Sale, 12 months or longer, Fair value	307,379	47,163
Securities Available-for-Sale, 12 months or longer, Unrealized losses	1,719	531
Securities Available-for-Sale, Fair value, Total	852,330	907,179
Securities Available-for-Sale, Unrealized losses, Total	6,567	12,309
Securities Held-to-Maturity, Less than 12 months, Fair value	97,120	134,909
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,247	5,148
Securities Held-to-Maturity, 12 months or longer, Fair value	20,406	7,564
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	391	87
Securities Held-to-Maturity, Fair value, Total	117,526	142,473
Securities Held-to-Maturity, Unrealized losses, Total	1,638	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	24,967	247,695
Securities Available-for-Sale, Less than 12 months, Unrealized losses	33	2,305
Securities Available-for-Sale, 12 months or longer, Fair value	243,874	19,838
Securities Available-for-Sale, 12 months or longer, Unrealized losses	1,126	162
Securities Available-for-Sale, Fair value, Total	268,841	267,533
Securities Available-for-Sale, Unrealized losses, Total	1,159	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	519,984	612,321
Securities Available-for-Sale, Less than 12 months, Unrealized losses	4,815	9,473
Securities Available-for-Sale, 12 months or longer, Fair value	63,505	27,325
Securities Available-for-Sale, 12 months or longer, Unrealized losses	593	369
Securities Available-for-Sale, Fair value, Total	583,489	639,646
Securities Available-for-Sale, Unrealized losses, Total	5,408	9,842
Securities Held-to-Maturity, 12 months or longer, Fair value	7,423	7,564
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	15	87
Securities Held-to-Maturity, Fair value, Total	7,423	7,564
Securities Held-to-Maturity, Unrealized losses, Total	15	87
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Less than 12 months, Fair value	97,120	134,909
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,247	5,148
Securities Held-to-Maturity, 12 months or longer, Fair value	12,983
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	376
Securities Held-to-Maturity, Fair value, Total	110,103	134,909
Securities Held-to-Maturity, Unrealized losses, Total	$ 1,623	$ 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.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 6
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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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