Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	$ 1,194,533	$ 1,262,761
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	9,000	7,687
Securities Available-for-Sale, Gross Unrealized Holding Losses	7,418	12,309
Securities Available-for-Sale, Total Fair value	1,196,115	1,258,139
Securities Held-to-Maturity, Amortized Cost	322,008	259,833
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	4,965	2,074
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	2,146	5,235
Securities Held-to-Maturity, Estimated Fair Value	324,827	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	1,314	2,467
Securities Available-for-Sale, Total Fair value	268,686	267,533
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	923,424	991,642
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	6,273	5,372
Securities Available-for-Sale, Gross Unrealized Holding Losses	6,104	9,842
Securities Available-for-Sale, Total Fair value	923,593	987,172
Securities Held-to-Maturity, Amortized Cost	61,840	71,211
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	1,065	1,097
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	24	87
Securities Held-to-Maturity, Estimated Fair Value	62,881	72,221
Other Equity Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	1,109	1,119
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,727	2,315
Securities Available-for-Sale, Total Fair value	3,836	3,434
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Amortized Cost	260,168	188,622
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	3,900	977
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	2,122	5,148
Securities Held-to-Maturity, Estimated Fair Value	$ 261,946	$ 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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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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