Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Abstract]
Due within one year, Amortized Cost	$ 92,028
Due after one year through five years, Amortized Cost	595,979
Due after five years through ten years, Amortized Cost	2,000,662
Due after ten years, Amortized Cost	1,392,449
Debt securities available-for-sale, amortized cost	4,081,118	$ 3,703,096
Due within one year, Fair Value	92,931
Due after one year through five years, Fair Value	626,018
Due after five years through ten years, Fair Value	2,133,751
Due after ten years, Fair Value	1,429,020
Debt securities available for sale at fair value	$ 4,281,720	$ 3,746,142

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 through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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