Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	$ 1,282,022	$ 1,299,980
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	15,539	15,010
Securities Available-for-Sale, Gross Unrealized Holding Losses	4,097	13,075
Securities Available-for-Sale, Total Fair value	1,293,464	1,301,915
Securities Held-to-Maturity, Amortized Cost	117,509	140,562
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	2,158
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	82
Securities Held-to-Maturity, Estimated Fair Value	119,585	143,490
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	546,888	546,886
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	260	11
Securities Available-for-Sale, Gross Unrealized Holding Losses	2,097	8,833
Securities Available-for-Sale, Total Fair value	545,051	538,064
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	734,014	751,974
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	13,766	13,421
Securities Available-for-Sale, Gross Unrealized Holding Losses	2,000	4,242
Securities Available-for-Sale, Total Fair value	745,780	761,153
Securities Held-to-Maturity, Amortized Cost	111,415	140,562
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	2,110	3,088
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	82	160
Securities Held-to-Maturity, Estimated Fair Value	113,443	143,490
Other Equity Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	1,120	1,120
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,513	1,578
Securities Available-for-Sale, Total Fair value	2,633	$ 2,698
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Amortized Cost	6,094
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	48
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	0
Securities Held-to-Maturity, Estimated Fair Value	$ 6,142