Investment Securities - Summary of Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Available for sale, Amortized Cost
Amortized Cost	$ 435,217	$ 400,718
Available for sale, Fair Value
Fair Value	439,023	410,624
Total debt securities
Available for sale, Amortized Cost
Within one year	5
After one year, but within five years	86,798
After five years, but within ten years	34,205
After ten years	299,927
Amortized Cost	420,935	382,317
Available for sale, Fair Value
Within one year	5
After one year, but within five years	86,542
After five years, but within ten years	35,079
After ten years	302,961
Fair Value	$ 424,587	$ 392,148

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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