Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Assets fair value	$ 102,230	$ 57,920
Cash equivalents | Money Market Funds
Assets:
Assets fair value	33,535	4,847
Cash equivalents | Commercial Paper
Assets:
Assets fair value	15,746	26,964
Cash equivalents | Corporate Debt Securities
Assets:
Assets fair value	1,351
Short-term Investments | Corporate Debt Securities
Assets:
Assets fair value	38,672	22,159
Short-term Investments | U.S. Government Agency Bonds
Assets:
Assets fair value	4,642
Short-term Investments | Asset-backed securities
Assets:
Assets fair value	8,284	3,950
Level 1
Assets:
Assets fair value	33,535	4,847
Level 1 | Cash equivalents | Money Market Funds
Assets:
Assets fair value	33,535	4,847
Level 2
Assets:
Assets fair value	68,695	53,073
Level 2 | Cash equivalents | Commercial Paper
Assets:
Assets fair value	15,746	26,964
Level 2 | Cash equivalents | Corporate Debt Securities
Assets:
Assets fair value	1,351
Level 2 | Short-term Investments | Corporate Debt Securities
Assets:
Assets fair value	38,672	22,159
Level 2 | Short-term Investments | U.S. Government Agency Bonds
Assets:
Assets fair value	4,642
Level 2 | Short-term Investments | Asset-backed securities
Assets:
Assets fair value	$ 8,284	$ 3,950