Fair Value of Financial Instruments - Schedule of Fair Value Measurement (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Total investments	$ 47,437	$ 100,218
Recurring
Investment [Line Items]
Total cash and cash equivalents	46,744	39,937
Total investments	47,437	100,218
Total assets measured at fair value	94,181	140,155
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total cash and cash equivalents	43,745	38,444
Total investments	12,579	22,120
Total assets measured at fair value	56,324	60,564
Recurring | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total cash and cash equivalents	2,999	1,493
Total investments	34,858	78,098
Total assets measured at fair value	37,857	79,591
Recurring | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total cash and cash equivalents	0	0
Total investments	0	0
Total assets measured at fair value	0	0
Recurring | Certificates of deposit
Investment [Line Items]
Total investments	5,663	10,787
Recurring | Certificates of deposit | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments	0	0
Recurring | Certificates of deposit | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments	5,663	10,787
Recurring | Certificates of deposit | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments	0	0
Recurring | US Treasury securities
Investment [Line Items]
Total investments	12,579	22,120
Recurring | US Treasury securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments	12,579	22,120
Recurring | US Treasury securities | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments	0	0
Recurring | US Treasury securities | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments	0	0
Recurring | US Agency securities
Investment [Line Items]
Total investments	3,998	7,980
Recurring | US Agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments	0	0
Recurring | US Agency securities | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments	3,998	7,980
Recurring | US Agency securities | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments	0	0
Recurring | Commercial paper
Investment [Line Items]
Total investments	2,491	17,025
Recurring | Commercial paper | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments	0	0
Recurring | Commercial paper | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments	2,491	17,025
Recurring | Commercial paper | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments	0	0
Recurring | Asset-backed securities
Investment [Line Items]
Total investments		11,998
Recurring | Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments		0
Recurring | Asset-backed securities | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments		11,998
Recurring | Asset-backed securities | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments		0
Recurring | Corporate notes and bonds
Investment [Line Items]
Total investments	22,706	30,308
Recurring | Corporate notes and bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total investments	0	0
Recurring | Corporate notes and bonds | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total investments	22,706	30,308
Recurring | Corporate notes and bonds | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total investments	0	0
Recurring | Money market funds
Investment [Line Items]
Total cash and cash equivalents	43,745	38,444
Recurring | Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total cash and cash equivalents	43,745	38,444
Recurring | Money market funds | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total cash and cash equivalents	0	0
Recurring | Money market funds | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total cash and cash equivalents	0	0
Recurring | Commercial paper
Investment [Line Items]
Total cash and cash equivalents	1,993	1,493
Recurring | Commercial paper | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total cash and cash equivalents	0	0
Recurring | Commercial paper | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total cash and cash equivalents	1,993	1,493
Recurring | Commercial paper | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total cash and cash equivalents	0	$ 0
Recurring | Corporate notes and bonds
Investment [Line Items]
Total cash and cash equivalents	1,006
Recurring | Corporate notes and bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment [Line Items]
Total cash and cash equivalents	0
Recurring | Corporate notes and bonds | Significant Other Observable Inputs (Level 2)
Investment [Line Items]
Total cash and cash equivalents	1,006
Recurring | Corporate notes and bonds | Significant Unobservable Inputs (Level 3)
Investment [Line Items]
Total cash and cash equivalents	$ 0