Securities (Scheduled Contractual Maturities of AFS Debt Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Amortized Cost
Due within one year	$ 756,955
Due after one year through five years	383,722
Due after five years through ten years	440,452
Due after ten years	2,890,565
Amortized Cost	4,471,694	$ 3,320,648
Fair Value
Due within one year	757,035
Due after one year through five years	388,413
Due after five years through ten years	451,219
Due after ten years	2,942,493
Total available-for-sale debt investment securities	4,539,160	3,317,214
Available for sale debt investment securities pledged as collateral, fair value	$ 710,391	$ 479,432

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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