Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 1,237,990	$ 1,028,883
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	28,756	453
Securities Available-for-Sale, Gross Unrealized Holding Losses	6,460	25,915
Debt Securities, Available-for-sale	1,260,286	1,003,421
Securities Held-to-Maturity, Amortized Cost		351,808
Securities Held-to-Maturity, Gross Unrecognized Holding Gains		3,289
Securities Held-to-Maturity, Gross Unrecognized Holding Losses		3,675
Securities held-to-maturity, fair value		351,422
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	934,468	1,028,883
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	10,373	453
Securities Available-for-Sale, Gross Unrealized Holding Losses	6,460	25,915
Debt Securities, Available-for-sale	938,381	1,003,421
Securities Held-to-Maturity, Amortized Cost		46,530
Securities Held-to-Maturity, Gross Unrecognized Holding Gains		87
Securities Held-to-Maturity, Gross Unrecognized Holding Losses		1,003
Securities held-to-maturity, fair value		45,614
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	303,522
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	18,383
Debt Securities, Available-for-sale	$ 321,905
Securities Held-to-Maturity, Amortized Cost		305,278
Securities Held-to-Maturity, Gross Unrecognized Holding Gains		3,202
Securities Held-to-Maturity, Gross Unrecognized Holding Losses		2,672
Securities held-to-maturity, fair value		$ 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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