Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	$ 1,368,902	$ 1,299,980
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	13,006	15,010
Securities Available-for-Sale, Gross Unrealized Holding Losses	11,643	13,075
Securities Available-for-Sale, Total Fair value	1,370,265	1,301,915
Securities Held-to-Maturity, Amortized Cost	121,527	140,562
Securities Held-to-Maturity, Estimated Fair Value	123,546	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	596,887	546,886
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		11
Securities Available-for-Sale, Gross Unrealized Holding Losses	7,968	8,833
Securities Available-for-Sale, Total Fair value	588,919	538,064
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	770,895	751,974
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	11,419	13,421
Securities Available-for-Sale, Gross Unrealized Holding Losses	3,675	4,242
Securities Available-for-Sale, Total Fair value	778,639	761,153
Securities Held-to-Maturity, Amortized Cost	121,527	140,562
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	2,152	3,088
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	133	160
Securities Held-to-Maturity, Estimated Fair Value	123,546	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	1,587	1,578
Securities Available-for-Sale, Total Fair value	$ 2,707	$ 2,698