Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

Summary of Available-for-sale 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