Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 985,045	$ 1,028,883
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4,924	453
Securities Available-for-Sale, Gross Unrealized Holding Losses	11,979	25,915
Debt Securities, Available-for-sale	977,990	1,003,421
Securities Held-to-Maturity, Amortized Cost	351,159	351,808
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	8,930	3,289
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	469	3,675
Securities held-to-maturity, fair value	359,620	351,422
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	985,045	1,028,883
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4,924	453
Securities Available-for-Sale, Gross Unrealized Holding Losses	11,979	25,915
Debt Securities, Available-for-sale	977,990	1,003,421
Securities Held-to-Maturity, Amortized Cost	46,462	46,530
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	154	87
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	339	1,003
Securities held-to-maturity, fair value	46,277	45,614
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Amortized Cost	304,697	305,278
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	8,776	3,202
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	130	2,672
Securities held-to-maturity, fair value	$ 313,343	$ 305,808

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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