Securities (Scheduled Contractual Maturities of AFS Debt Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Due within one year	$ 588,392
Due after one year through five years	314,312
Due after five years through ten years	240,566
Due after ten years	2,517,143
Amortized Cost	3,660,413	$ 3,320,648
Fair Value
Due within one year	590,461
Due after one year through five years	319,938
Due after five years through ten years	252,057
Due after ten years	2,533,487
Total available-for-sale debt investment securities	3,695,943	3,317,214
Available for sale debt investment securities pledged as collateral, fair value	$ 742,410	$ 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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