The Business and Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Separate Account Investment [Line Items]
Short-term investments	$ 42,449	$ 96,574
Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	48,938	11,854
Short-term investments	42,449	96,574
Total assets	91,387	108,428
Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	48,938	11,854
Short-term investments	6,021	22,493
Total assets	54,959	34,347
Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Short-term investments	36,428	74,081
Total assets	36,428	74,081
Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Short-term investments	0	0
Total assets	0	0
Money market funds | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	48,938	11,854
Money market funds | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	48,938	11,854
Money market funds | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Money market funds | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
U.S. treasury securities | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	6,021	22,493
U.S. treasury securities | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	6,021	22,493
U.S. treasury securities | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
U.S. treasury securities | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Commercial paper | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	18,594	43,119
Commercial paper | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Commercial paper | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	18,594	43,119
Commercial paper | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Corporate bonds | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	17,834	30,962
Corporate bonds | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Corporate bonds | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	17,834	30,962
Corporate bonds | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	$ 0	$ 0