Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

We measure certain financial instruments at fair value using a fair value hierarchy. In the hierarchy, assets are classified based on the lowest level inputs used in valuation into the following categories:

• Level 1 — Quoted prices in active markets for identical assets and liabilities;

• Level 2 — Observable inputs including quoted market prices for similar assets and liabilities in active markets, quoted prices for identical assets and liabilities in inactive markets, or inputs that are corroborated by observable market data; and

• Level 3 — Unobservable inputs.

The following tables summarize assets that are measured at fair value on a recurring basis:

	March 31, 2019
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	20,732	$	—	$	—	$	20,732
Commercial paper	—		4,489		—		4,489
	$	20,732	$	4,489	$	—	$	25,221
Short-term investments
Commercial paper	$	—	$	66,166	$	—	$	66,166
Corporate bonds	—		12,678		—		12,678
U.S. Treasury and agency obligations	—		52,170		—		52,170
	$	—	$	131,014	$	—	$	131,014

	December 31, 2018
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents
Money market funds	$	38,022	$	—	$	—	$	38,022
	$	38,022	$	—	$	—	$	38,022
Short-term investments
Commercial paper	$	—	$	79,634	$	—	$	79,634
Corporate bonds	—		16,119		—		16,119
U.S. Treasury and agency obligations	—		22,366		—		22,366
	$	—	$	118,119	$	—	$	118,119

We did not have any liabilities measured and recorded at fair value at March 31, 2019, and December 31, 2018.