Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Assets fair value	$ 62,220	$ 57,920
Cash equivalents | Money Market Funds
Assets:
Assets fair value	29,240	4,847
Cash equivalents | Commercial Paper
Assets:
Assets fair value	5,797	26,964
Short-term Investments | Corporate Debt Securities
Assets:
Assets fair value	24,090	22,159
Short-term Investments | Asset-backed securities
Assets:
Assets fair value	3,093	3,950
Level 1
Assets:
Assets fair value	29,240	4,847
Level 1 | Cash equivalents | Money Market Funds
Assets:
Assets fair value	29,240	4,847
Level 2
Assets:
Assets fair value	32,980	53,073
Level 2 | Cash equivalents | Commercial Paper
Assets:
Assets fair value	5,797	26,964
Level 2 | Short-term Investments | Corporate Debt Securities
Assets:
Assets fair value	24,090	22,159
Level 2 | Short-term Investments | Asset-backed securities
Assets:
Assets fair value	$ 3,093	$ 3,950