Marketable Securities

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

3.	Marketable Securities

The following table summarizes the Company’s available-for-sale marketable securities as of September 30, 2019 and December 31, 2018 at net book value:

	September 30, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury securities	$	176,443	$	188	$	(5	)	$	176,626
Financial institution debt securities		53,699		124		-			53,823
Corporate debt securities		18,900		6		-			18,906
Other asset-backed securities		7,972		23		-			7,995
Total	$	257,014	$	341	$	(5	)	$	257,350

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury securities	$	165,959	$	2	$	(13	)	$	165,948
Financial institution debt securities		65,436		1		(17	)		65,420
Corporate debt securities		23,836		-		(1	)		23,835
Total	$	255,231	$	3	$	(31	)	$	255,203

The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. At September 30, 2019 and December 31, 2018, the balance in the Company’s accumulated other comprehensive income (loss) was composed of activity related to the Company’s available-for-sale marketable securities. There were no material realized gains or losses in the three or nine months ended September 30, 2019, and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income (loss) during the period. The Company did not have any securities in a material unrealized loss position at September 30, 2019.