Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	$ 1,222,447	$ 1,262,761
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	8,322	7,687
Securities Available-for-Sale, Gross Unrealized Holding Losses	11,372	12,309
Securities Available-for-Sale, Total Fair value	1,219,397	1,258,139
Securities Held-to-Maturity, Amortized Cost	284,460	259,833
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	2,717	2,074
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	4,022	5,235
Securities Held-to-Maturity, Estimated Fair Value	283,155	256,672
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	270,000	270,000
Securities Available-for-Sale, Gross Unrealized Holding Losses	1,579	2,467
Securities Available-for-Sale, Total Fair value	268,421	267,533
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	951,328	991,642
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	6,044	5,372
Securities Available-for-Sale, Gross Unrealized Holding Losses	9,793	9,842
Securities Available-for-Sale, Total Fair value	947,579	987,172
Securities Held-to-Maturity, Amortized Cost	65,221	71,211
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	1,019	1,097
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	77	87
Securities Held-to-Maturity, Estimated Fair Value	66,163	72,221
Other Equity Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	1,119	1,119
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,278	2,315
Securities Available-for-Sale, Total Fair value	3,397	3,434
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Amortized Cost	219,239	188,622
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	1,698	977
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	3,945	5,148
Securities Held-to-Maturity, Estimated Fair Value	$ 216,992	$ 184,451

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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-Publisher FASB
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