Investment Securities (Amortized Cost And Estimated Fair Value Of Investments In Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 985,045	$ 1,028,883
Securities Available-for-Sale, Total Fair value	977,990	1,003,421
Securities Held-to-Maturity, Amortized Cost	351,159	351,808
Securities held-to-maturity, fair value	359,620	351,422
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	4,024
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value	$ 4,098
Held to Maturity Securities weighted avg yield five through ten	3.04%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	$ 300,673
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	$ 309,245
Held to Maturity Securities Debt Maturities Years Over Ten weighted avg yield	3.69%
Securities Held-to-Maturity, Amortized Cost	$ 304,697	305,278
Securities held-to-maturity, fair value	$ 313,343	305,808
Held to Maturity Securities weighted avg yield	3.68%
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 985,045	1,028,883
Securities Available-for-Sale, Total Fair value	$ 977,990	1,003,421
Available for Sale Securities Weighted Avg Yield	2.35%
Securities Held-to-Maturity, Amortized Cost	$ 46,462	46,530
Securities held-to-maturity, fair value	$ 46,277	$ 45,614
Held to Maturity Securities weighted avg yield	2.83%

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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