INVESTMENT SECURITIES

9 Months Ended

Sep. 30, 2018

Investments, Debt and Equity Securities [Abstract]

INVESTMENT SECURITIES

Our investments as of September 30, 2018 and December 31, 2017 are classified as held-to-maturity. Held-to-maturity investments are recorded at amortized cost.

The following tables summarize our investment securities at September 30, 2018 and December 31, 2017:

			September 30, 2018
(in thousands)	Amortized cost, as adjusted		Gross unrealized holding gains		Gross unrealized holding losses		Estimated fair value
Short-term investments:
Obligations of domestic governmental agencies (maturing between October 2018 and September 2019) (held-to-maturity)	$	27,024	$	—	$	19	$	27,005
Total short-term investment securities	$	27,024	$	—	$	19	$	27,005

	December 31, 2017
(in thousands)	Amortized cost, as adjusted		Gross unrealized holding gains		Gross unrealized holding losses		Estimated fair value
Short-term investments:
Obligations of domestic governmental agencies (maturing between January 2018 and November 2018) (held-to-maturity)	$	27,999		--	$	35	$	27,964
Total short-term investment securities	$	27,999		--	$	35	$	27,964