INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Value - Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due after one year through five years	$ 10,894
Due after five years through ten years	35,203
Due after ten years	27,125
Mortgage-backed securities	370,706
Amortized Cost	443,928	$ 310,484
Fair Value
Due after one year through five years	9,710
Due after five years through ten years	35,620
Due after ten years	26,547
Mortgage-backed securities	365,877
Fair Value	$ 437,754	$ 307,130

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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