Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 662,276	$ 261,855
Securities Available-for-Sale, Less than 12 months, Unrealized losses	17,518	2,856
Securities Available-for-Sale, 12 months or longer, Fair value	294,713	536,586
Securities Available-for-Sale, 12 months or longer, Unrealized losses	16,197	7,553
Securities Available-for-Sale, Fair value, Total	956,989	798,441
Securities Available-for-Sale, Unrealized losses, Total	33,715	10,409
Securities Held-to-Maturity, Less than 12 months, Fair value	160,664	33,975
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	2,780	232
Securities Held-to-Maturity, 12 months or longer, Fair value	49,748	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	1,752	519
Securities Held-to-Maturity, Fair value, Total	210,412	79,473
Securities Held-to-Maturity, Unrealized losses, Total	4,532	751
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		24,931
Securities Available-for-Sale, Less than 12 months, Unrealized losses		70
Securities Available-for-Sale, 12 months or longer, Fair value		217,789
Securities Available-for-Sale, 12 months or longer, Unrealized losses		2,210
Securities Available-for-Sale, Fair value, Total		242,720
Securities Available-for-Sale, Unrealized losses, Total		2,280
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	662,276	236,924
Securities Available-for-Sale, Less than 12 months, Unrealized losses	17,518	2,786
Securities Available-for-Sale, 12 months or longer, Fair value	294,713	318,797
Securities Available-for-Sale, 12 months or longer, Unrealized losses	16,197	5,343
Securities Available-for-Sale, Fair value, Total	956,989	555,721
Securities Available-for-Sale, Unrealized losses, Total	33,715	8,129
Securities Held-to-Maturity, Less than 12 months, Fair value	45,521	7,331
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,246	38
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	45,521	7,331
Securities Held-to-Maturity, Unrealized losses, Total	1,246	38
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Less than 12 months, Fair value	115,143	26,644
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,534	194
Securities Held-to-Maturity, 12 months or longer, Fair value	49,748	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	1,752	519
Securities Held-to-Maturity, Fair value, Total	164,891	72,142
Securities Held-to-Maturity, Unrealized losses, Total	$ 3,286	$ 713

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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