Investment Securities - Contractual Maturities of Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Amortized Cost
Due in one year	$ 92,432
Due after one year through five years	171,778
Due after five years through ten years	203,555
Due after ten years	214,081
Residential mortgage-backed securities	1,451,581
Amortized Cost	2,133,427	$ 2,336,095
Fair Value
Due in one year	93,313
Due after one year through five years	179,833
Due after five years through ten years	215,200
Due after ten years	210,931
Residential mortgage-backed securities	1,495,599
Total investment securities held to maturity	$ 2,194,876	$ 2,358,720

Amount of investment in debt security measured at amortized cost (held-to-maturity).

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