Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Abstract]
Due within one year, Amortized Cost	$ 112,412
Due after one year through five years, Amortized Cost	412,269
Due after five years through ten years, Amortized Cost	1,592,778
Due after ten years, Amortized Cost	1,182,684
Debt securities available-for-sale, amortized cost	3,300,143	$ 3,210,615
Due within one year, Fair Value	112,594
Due after one year through five years, Fair Value	416,294
Due after five years through ten years, Fair Value	1,650,631
Due after ten years, Fair Value	1,188,053
Debt securities available-for-sale, Fair Value	$ 3,367,572	$ 3,167,448

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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Fair value 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 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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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 second through fifth 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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