Investment Securities (Amortized Cost And Estimated Fair Value Of Investments In Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
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, fair value	123,546	143,490
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	100,000
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	$ 99,911
Available for Sale Securities Debt Maturities two through five Weighted Avg Yield	1.05%
Securities Available-for-Sale, Due five through ten years, Amortized cost	$ 496,887
Securities Available-for-Sale, Due five through ten years, Fair value	$ 489,008
Available for Sale Securities Debt Maturities After Five Through Ten Years Weighted Avg Yield	2.36%
Securities Available-for-Sale, Total, Amortized cost	$ 596,887
Securities Available-for-Sale, Total Fair value	$ 588,919	538,064
Available for Sale Securities Weighted Avg Yield	2.14%
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total, Amortized cost	$ 770,895
Securities Available-for-Sale, Total Fair value	$ 778,639	761,153
Available for Sale Securities Weighted Avg Yield	2.32%
Securities Held-to-Maturity, Amortized Cost	$ 121,527	140,562
Securities held-to-maturity, fair value	$ 123,546	$ 143,490
Held to Maturity Securities weighted avg yield	3.52%