Investment Securities - Investment securities and summary of the gains (losses) related to securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available for sale securities:
Amortized Cost	$ 222,358	$ 252,958
Unrealized gains		3,315
Unrealized losses		(5)
Fair value	222,478	256,268
Commercial paper
Available for sale securities:
Amortized Cost		1,976
Unrealized gains		1
Fair value		1,977
Corporate bonds
Available for sale securities:
Amortized Cost	222,358	250,982
Unrealized gains	1,505	3,314
Unrealized losses	(1,385)	(5)
Fair value	$ 222,478	$ 254,291

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount 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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