Fair Value Measurements - Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	$ 27,041
Over One Year Through Five Years	40,505
Over Five Years	0
Total	67,546	$ 0
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	6,075
Over One Year Through Five Years	15,265
Over Five Years	0
Total	21,340
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	14,543
Over One Year Through Five Years	0
Over Five Years	0
Total	14,543
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	560
Over One Year Through Five Years	13,978
Over Five Years	0
Total	14,538
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
One Year or Less	5,863
Over One Year Through Five Years	11,262
Over Five Years	0
Total	$ 17,125