Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets Measured on Recurring Basis

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

	Fair Value Measurements at March 31, 2019
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	39,971	$	39,971	$	—	$	—
Corporate securities and commercial paper		91,910		—		91,910		—
U.S. government treasury and agency securities		111,255		—		111,255		—
	$	243,136	$	39,971	$	203,165	$	—

	Fair Value Measurements at December 31, 2018
	Total		Level 1		Level 2		Level 3
Assets
Money market funds	$	45,017	$	45,017	$	—	$	—
U.S. government agency obligations		103,940		—		103,940		—
Corporate securities and commercial paper		110,768		—		110,768		—
	$	259,725	$	45,017	$	214,708	$	—

Schedule of Investments Classified as Available for Sale Securities with Contractual Maturities

Classified as (with contractual maturities):

	March 31, 2019		December 31, 2018
Cash and Cash equivalents	$	68,499	$	71,064
Short-term investments (due within one year)		173,436		185,480
Long-term investments (due between one and two years)		1,201		3,181
	$	243,136	$	259,725

Schedule of Available for Sale Securities at Fair Value Measurements

	Fair Value Measurements at March 31, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
Money market funds	$	39,971	$	—	$	—		$	39,971
Corporate securities and commercial paper		91,913		—		(3	)		91,910
U.S. government treasury and agency securities		111,223		32		—			111,255
	$	243,107	$	32	$	(3	)	$	243,136

	Fair Value Measurements at December 31, 2018
	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
Money market funds	$	45,017	$	—	$	—		$	45,017
U.S. government agency obligations		103,957		—		(17	)		103,940
Corporate securities and commercial paper		110,859		—		(91	)		110,768
	$	259,833	$	—	$	(108	)	$	259,725