Securities (Scheduled Contractual Maturities of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amortized Cost
Due within one year	$ 1,100,414
Due after one year through five years	430,577
Due after five years through ten years	185,633
Due after ten years	1,543,160
Total available-for-sale debt investment securities, Amortized Cost	3,259,784	$ 2,806,900
Fair Value
Due within one year	1,099,412
Due after one year through five years	429,725
Due after five years through ten years	189,981
Due after ten years	1,564,916
Total available-for-sale debt investment securities	3,284,034	2,741,847
Available for sale debt investment securities pledged as collateral, fair value	$ 524,413	$ 435,833

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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