Investment Securities - Summary of Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Carrying value of investment securities pledged	$ 67,200
Amortized Cost
Amortized Cost	224,637
Fair Value
Fair Value	216,714
Total debt securities
Amortized Cost
Within one year	0
After one year, but within five	46,668
After five years, but within ten	28,213
After ten years	140,630
Amortized Cost	215,511	$ 215,574
Fair Value
Within one year	0
After one year, but within five	45,665
After five years, but within ten	26,818
After ten years	135,134
Fair Value	$ 207,617	$ 214,941

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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