Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 775,132	$ 261,855
Securities Available-for-Sale, Less than 12 months, Unrealized losses	19,613	2,856
Securities Available-for-Sale, 12 months or longer, Fair value	279,486	536,586
Securities Available-for-Sale, 12 months or longer, Unrealized losses	16,696	7,553
Securities Available-for-Sale, Fair value, Total	1,054,618	798,441
Securities Available-for-Sale, Unrealized losses, Total	36,309	10,409
Securities Held-to-Maturity, Less than 12 months, Fair value	169,754	33,975
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	3,473	232
Securities Held-to-Maturity, 12 months or longer, Fair value	58,541	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	2,086	519
Securities Held-to-Maturity, Fair value, Total	228,295	79,473
Securities Held-to-Maturity, Unrealized losses, Total	5,559	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	775,132	236,924
Securities Available-for-Sale, Less than 12 months, Unrealized losses	19,613	2,786
Securities Available-for-Sale, 12 months or longer, Fair value	279,486	318,797
Securities Available-for-Sale, 12 months or longer, Unrealized losses	16,696	5,343
Securities Available-for-Sale, Fair value, Total	1,054,618	555,721
Securities Available-for-Sale, Unrealized losses, Total	36,309	8,129
Securities Held-to-Maturity, Less than 12 months, Fair value	40,016	7,331
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,236	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	40,016	7,331
Securities Held-to-Maturity, Unrealized losses, Total	1,236	38
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Less than 12 months, Fair value	129,738	26,644
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	2,237	194
Securities Held-to-Maturity, 12 months or longer, Fair value	58,541	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	2,086	519
Securities Held-to-Maturity, Fair value, Total	188,279	72,142
Securities Held-to-Maturity, Unrealized losses, Total	$ 4,323	$ 713

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months.

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