Investment Securities (Schedule Of Unrealized Loss On Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Gain (Loss) on Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	$ 482,971	$ 494,068
Securities Available-for-Sale, Less than 12 months, Unrealized losses	4,856	11,462
Securities Available-for-Sale, 12 months or longer, Fair value	215	221
Securities Available-for-Sale, 12 months or longer, Unrealized losses	13	14
Securities Available-for-Sale, Fair value, Total	483,186	494,289
Securities Available-for-Sale, Unrealized losses, Total	4,869	11,476
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Gain (Loss) on Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	74,936	74,379
Securities Available-for-Sale, Less than 12 months, Unrealized losses	1,399	1,956
Securities Available-for-Sale, Fair value, Total	74,936	74,379
Securities Available-for-Sale, Unrealized losses, Total	1,399	1,956
Obligations Of States And Political Subdivisions [Member]
Gain (Loss) on Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value		1,459
Securities Available-for-Sale, Less than 12 months, Unrealized losses		52
Securities Available-for-Sale, Fair value, Total		1,459
Securities Available-for-Sale, Unrealized losses, Total		52
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Gain (Loss) on Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	407,954	418,156
Securities Available-for-Sale, Less than 12 months, Unrealized losses	3,427	9,425
Securities Available-for-Sale, Fair value, Total	407,954	418,156
Securities Available-for-Sale, Unrealized losses, Total	3,427	9,425
Securities Held-to-Maturity, Less than 12 months, Fair value	312,382	297,584
Securities Held-to-Maturity, Less than 12 months, Unrealized losses	5,177	4,620
Securities Held-to-Maturity, Fair value, Total	312,382	297,584
Securities Held-to-Maturity, Unrealized losses, Total	5,177	4,620
Other Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Securities Available-for-Sale, Less than 12 months, Fair value	81	74
Securities Available-for-Sale, Less than 12 months, Unrealized losses	30	29
Securities Available-for-Sale, 12 months or longer, Fair value	215	221
Securities Available-for-Sale, 12 months or longer, Unrealized losses	13	14
Securities Available-for-Sale, Fair value, Total	296	295
Securities Available-for-Sale, Unrealized losses, Total	$ 43	$ 43