Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets:
Assets fair value	$ 97,309	$ 102,230
Cash equivalents | Money Market Funds
Assets:
Assets fair value	33,546	33,535
Cash equivalents | Commercial Paper
Assets:
Assets fair value	9,224	15,746
Cash equivalents | Corporate Debt Securities
Assets:
Assets fair value		1,351
Short-term Investments | Corporate Debt Securities
Assets:
Assets fair value	42,544	38,672
Short-term Investments | U.S. Government Agency Bonds
Assets:
Assets fair value	4,628	4,642
Short-term Investments | Asset-backed securities
Assets:
Assets fair value	7,367	8,284
Level 1
Assets:
Assets fair value	33,546	33,535
Level 1 | Cash equivalents | Money Market Funds
Assets:
Assets fair value	33,546	33,535
Level 2
Assets:
Assets fair value	63,763	68,695
Level 2 | Cash equivalents | Commercial Paper
Assets:
Assets fair value	9,224	15,746
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	42,544	38,672
Level 2 | Short-term Investments | U.S. Government Agency Bonds
Assets:
Assets fair value	4,628	4,642
Level 2 | Short-term Investments | Asset-backed securities
Assets:
Assets fair value	$ 7,367	$ 8,284