Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

We measure cash, cash equivalents and short-term investments at fair value on a recurring basis. The fair values of these such assets were as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	56,931	$	56,931	$	—	$	—
U.S. treasury bills and government agency obligations		140,626		140,626		—		—
U.S. corporate debt securities		80,170		—		80,170		—
Foreign corporate debt securities		23,203		—		23,203		—
U.S. commercial paper		32,801		—		32,801		—
Foreign commercial paper		57,241		—		57,241		—
Total	$	390,972	$	197,557	$	193,415	$	—

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	22,751	$	22,751	$	—	$	—
U.S. treasury bills and government agency obligations		59,741	$	59,741	$	—	$	—
U.S. corporate debt securities		59,087		—		59,087		—
Foreign corporate debt securities		5,046		—		5,046		—
U.S. commercial paper		61,885		—		61,885		—
Foreign commercial paper		123,861		—		123,861		—
Total	$	332,371	$	82,492	$	249,879	$	—