Investment Securities (Amortized Cost And Estimated Fair Value Of Investments In Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 1,237,990	$ 1,028,883
Securities Available-for-Sale, Total Fair value	1,260,286	1,003,421
Securities Held-to-Maturity, Amortized Cost		351,808
Securities held-to-maturity, fair value		351,422
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	3,998
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value	$ 4,140
Debt Securities, Available-for-sale, Maturity, after Five Through Ten Years, Weighted Average Yield	3.04%
Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost	$ 299,524
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value	$ 317,765
Debt Securities, Available-for-sale, Maturity, after 10 Years, Weighted Average Yield	3.69%
Debt Securities, Available-for-sale, Amortized Cost	$ 303,522
Securities Available-for-Sale, Total Fair value	$ 321,905
Available for Sale Securities Weighted Avg Yield	3.68%
Securities Held-to-Maturity, Amortized Cost		305,278
Securities held-to-maturity, fair value		305,808
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 934,468	1,028,883
Securities Available-for-Sale, Total Fair value	$ 938,381	1,003,421
Available for Sale Securities Weighted Avg Yield	2.37%
Securities Held-to-Maturity, Amortized Cost		46,530
Securities held-to-maturity, fair value		$ 45,614

Available for Sale Securities Weighted Avg Yield

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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).

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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), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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