Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Quoted Prices in Active Markets for Identical Assets (Level 1)
Schedule of Available-for-sale Securities
Total	$ 35,449	$ 37,948
Significant Other Observable Inputs (Level 2)
Schedule of Available-for-sale Securities
Total	0	0
Significant Unobservable Inputs (Level 3)
Schedule of Available-for-sale Securities
Total	0	0
Money market funds (included in cash and cash equivalents) | Quoted Prices in Active Markets for Identical Assets (Level 1)
Schedule of Available-for-sale Securities
Money market funds (included in cash and cash equivalents)	35,449	37,948
Money market funds (included in cash and cash equivalents) | Significant Other Observable Inputs (Level 2)
Schedule of Available-for-sale Securities
Money market funds (included in cash and cash equivalents)	0	0
Money market funds (included in cash and cash equivalents) | Significant Unobservable Inputs (Level 3)
Schedule of Available-for-sale Securities
Money market funds (included in cash and cash equivalents)	$ 0	$ 0