Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 547,752	$ 261,855
Securities Available-for-Sale, Less than 12 months, Unrealized losses	12,583	2,856
Securities Available-for-Sale, 12 months or longer, Fair value	450,284	536,586
Securities Available-for-Sale, 12 months or longer, Unrealized losses	29,986	7,553
Securities Available-for-Sale, Fair value, Total	998,036	798,441
Securities Available-for-Sale, Unrealized losses, Total	42,569	10,409
Securities Held-to-Maturity, Less than 12 months, Fair value	184,778	33,975
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	4,206	232
Securities Held-to-Maturity, 12 months or longer, Fair value	76,373	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	3,232	519
Securities Held-to-Maturity, Fair value, Total	261,151	79,473
Securities Held-to-Maturity, Unrealized losses, Total	7,438	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	547,752	236,924
Securities Available-for-Sale, Less than 12 months, Unrealized losses	12,583	2,786
Securities Available-for-Sale, 12 months or longer, Fair value	450,284	318,797
Securities Available-for-Sale, 12 months or longer, Unrealized losses	29,986	5,343
Securities Available-for-Sale, Fair value, Total	998,036	555,721
Securities Available-for-Sale, Unrealized losses, Total	42,569	8,129
Securities Held-to-Maturity, Less than 12 months, Fair value	32,704	7,331
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	1,165	38
Securities Held-to-Maturity, 12 months or longer, Fair value	6,944
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	221
Securities Held-to-Maturity, Fair value, Total	39,648	7,331
Securities Held-to-Maturity, Unrealized losses, Total	1,386	38
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Less than 12 months, Fair value	152,074	26,644
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	3,041	194
Securities Held-to-Maturity, 12 months or longer, Fair value	69,429	45,498
Securities Held-to-Maturity, 12 months or longer, Unrealized losses	3,011	519
Securities Held-to-Maturity, Fair value, Total	221,503	72,142
Securities Held-to-Maturity, Unrealized losses, Total	$ 6,052	$ 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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