Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurement

The following tables represent the financial instruments measured at fair value on a recurring basis on the financial statements of the Company and the valuation approach applied to each class of financial instruments at December 31 (see Note 2, Summary of Significant Accounting Policies for further information):

	2018
	(in thousands)
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	38,444	$	—	$	—	$	38,444
Commercial paper	—		1,493		—		1,493
Total cash and cash equivalents	$	38,444	$	1,493	$	—	$	39,937
Investments:
Certificates of deposit	—		10,787		—		10,787
US Treasury securities	22,120		—		—		22,120
US Agency securities	—		7,980		—		7,980
Commercial paper	—		17,025		—		17,025
Asset-backed securities	—		11,998		—		11,998
Corporate notes and bonds	—		30,308		—		30,308
Total investments	22,120		78,098		—		100,218
Total assets measured at fair value	$	60,564	$	79,591	$	—	$	140,155

	2017
	(in thousands)
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	7,832	$	—	$	—	$	7,832
Investments:
Certificates of deposit	—		13,441		—		13,441
US Treasury securities	14,716		—		—		14,716
US Agency securities	—		8,459		—		8,459
Commercial paper	—		9,171		—		9,171
Asset-backed securities	—		3,025		—		3,025
Corporate notes and bonds	—		31,836		—		31,836
Total investments	14,716		65,932		—		80,648
Total assets measured at fair value	$	22,548	$	65,932	$	—	$	88,480