Available-for-Sale Securities and Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Summary of Financial Instruments Measured at Fair Value on a Recurring Basis

The following tables set forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):

	June 30, 2019
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash and money market funds	$	72,564	$	—	$	—	$	72,564
Total cash and cash equivalents	$	72,564	$	—	$	—	$	72,564
Investments:
Agency securities	$	—	$	21,256	$	—	$	21,256
Corporate securities		—		44,153		—		44,153
Commercial paper		—		11,033		—		11,033
U.S. government securities		—		101,250		—		101,250
Total investments	$	—	$	177,692	$	—	$	177,692

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash and money market funds	$	107,511	$	—	$	—	$	107,511
Total cash and cash equivalents	$	107,511	$	—	$	—	$	107,511
Investments:
Agency securities		—		17,352		—		17,352
Corporate securities		—		54,474		—		54,474
Commercial paper		—		5,965		—		5,965
U.S. government securities		—		118,630		—		118,630
Total investments	$	—	$	196,421	$	—	$	196,421

Summary of Aggregate Market Value, Cost Basis and Gross Unrealized Gains and Losses of Available-for-Sale Investments by Security Type

The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents and investments, as of June 30, 2019 and December 31, 2018, are as follows (in thousands):

	June 30, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Total Fair Value
Agency securities	$	21,243	$	13	$	—	$	21,256
Corporate securities		44,051		102		—		44,153
Commercial paper		11,033		—		—		11,033
U.S. government securities		101,129		121		—		101,250
Total available-for-sale investments	$	177,456	$	236	$	—	$	177,692

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Fair Value
Agency securities	$	17,361	$	—	$	(9	)	$	17,352
Corporate securities		54,536		—		(62	)		54,474
Commercial paper		5,965		—		—			5,965
U.S. government securities		118,667		14		(51	)		118,630
Total available-for-sale investments	$	196,529	$	14	$	(122	)	$	196,421