Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on Recurring Basis

Assets measured at fair value on a recurring basis were as follows:

Description	September 30, 2019		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	36,883	$	36,883	$	—	$	—
Repurchase agreements		41,200		—		41,200		—
U.S. Treasury securities		9		9		—		—
Total cash equivalents	$	78,092	$	36,892	$	41,200	$	—
Short-term investments:
Asset-backed securities	$	11,594	$	—	$	11,594	$	—
Commercial paper		23,074		—		23,074		—
Corporate debt securities		92,628		—		92,628		—
U.S. Treasury securities		64,817		—		64,817		—
Total short-term investments	$	192,113	$	—	$	192,113	$	—
Total financial assets	$	270,205	$	36,892	$	233,313	$	—
Description	December 31, 2018		Quoted Prices (Unadjusted) in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents:
Money market mutual funds	$	31,740	$	31,740	$	—	$	—
Commercial paper		5,974		—		5,974		—
U.S. Treasury securities		35		35		—		—
Total cash equivalents	$	37,749	$	31,775	$	5,974	$	—
Short-term investments:
Asset-backed securities	$	19,520	$	—	$	19,520	$	—
Commercial paper		72,597		—		72,597		—
Corporate debt securities		54,461		—		54,461		—
U.S. Treasury securities		29,939		—		29,939		—
Total short-term investments	$	176,517	$	—	$	176,517	$	—
Total financial assets	$	214,266	$	31,775	$	182,491	$	—