Cash, Cash Equivalents and Investment Debt Securities (Tables)

9 Months Ended

Sep. 30, 2019

Cash, Cash Equivalents, and Investment Debt Securities [Abstract]

Cash, Cash Equivalents and Investment Debt Securities

The following table summarizes the Company’s cash, cash equivalents and investment debt securities as of September 30, 2019 and December 31, 2018:

	As of September 30, 2019
			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses		Fair Value
	(in thousands)
Cash and cash equivalents:
Cash and money market funds	$	63,377	$	—	$	—	$	63,377
Total cash and cash equivalents		63,377		—		—		63,377
Investment debt securities:
Commercial paper		70,009		62		(8)		70,063
Corporate debt securities		574,046		984		(95)		574,935
U.S. government and agency securities		3,992		4		—		3,996
Total investment debt securities		648,047		1,050		(103)		648,994
Total cash, cash equivalents and investment debt securities	$	711,424	$	1,050	$	(103)	$	712,371

	As of December 31, 2018
			Gross		Gross
			Unrealized		Unrealized
	Amortized Cost		Gains		Losses		Fair Value
	(in thousands)
Cash and cash equivalents:
Cash and money market funds	$	43,248	$	—	$	—	$	43,248
Investment debt securities:
Commercial paper		34,353		—		(26)		34,327
Corporate debt securities		349,854		27		(704)		349,177
U.S. government and agency securities		9,410		5		(7)		9,408
Total investment debt securities		393,617		32		(737)		392,912
Total cash, cash equivalents and investment debt securities	$	436,865	$	32	$	(737)	$	436,160