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Summary of Significant Accounting Policies - Summary of Fair Value Measurement Financial Asset and Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Assets [Abstract] |  |
Cash and cash equivalents | $ 73,200 | $ 146,200
Securities | 89,284 |
Total assets measured at fair value | 162,506 | 160,849
Money market funds |  |
Assets [Abstract] |  |
Cash and cash equivalents | 46,149 | 46,257
Government-sponsored enterprises |  |
Assets [Abstract] |  |
Marketable securities | 13,222 |
U.S Treasury securities |  |
Assets [Abstract] |  |
Marketable securities |  | 12,488
Corporate debt securities |  |
Assets [Abstract] |  |
Marketable securities |  | 100,214
Securities | 103,135 |
Common stock warrants |  |
Assets [Abstract] |  |
Common stock warrants |  | 1,890
Quoted Prices in Active Markets for Identical Assets, Level 1 |  |
Assets [Abstract] |  |
Total assets measured at fair value | 46,149 | 46,257
Quoted Prices in Active Markets for Identical Assets, Level 1 | Money market funds |  |
Assets [Abstract] |  |
Cash and cash equivalents | 46,149 | 46,257
Quoted Prices in Active Markets for Identical Assets, Level 1 | Government-sponsored enterprises |  |
Assets [Abstract] |  |
Marketable securities | 0 |
Quoted Prices in Active Markets for Identical Assets, Level 1 | U.S Treasury securities |  |
Assets [Abstract] |  |
Marketable securities |  | 0
Quoted Prices in Active Markets for Identical Assets, Level 1 | Corporate debt securities |  |
Assets [Abstract] |  |
Marketable securities |  | 0
Securities | 0 |
Quoted Prices in Active Markets for Identical Assets, Level 1 | Common stock warrants |  |
Assets [Abstract] |  |
Common stock warrants |  | 0
Significant Other Observable Inputs, Level 2 |  |
Assets [Abstract] |  |
Total assets measured at fair value | 116,357 | 112,702
Significant Other Observable Inputs, Level 2 | Money market funds |  |
Assets [Abstract] |  |
Cash and cash equivalents | 0 | 0
Significant Other Observable Inputs, Level 2 | Government-sponsored enterprises |  |
Assets [Abstract] |  |
Marketable securities | 13,222 |
Significant Other Observable Inputs, Level 2 | U.S Treasury securities |  |
Assets [Abstract] |  |
Marketable securities |  | 12,488
Significant Other Observable Inputs, Level 2 | Corporate debt securities |  |
Assets [Abstract] |  |
Marketable securities |  | 100,214
Securities | 103,135 |
Significant Other Observable Inputs, Level 2 | Common stock warrants |  |
Assets [Abstract] |  |
Common stock warrants |  | 0
Significant Unobservable Inputs, Level 3 |  |
Assets [Abstract] |  |
Total assets measured at fair value | 0 | 1,890
Significant Unobservable Inputs, Level 3 | Money market funds |  |
Assets [Abstract] |  |
Cash and cash equivalents | 0 | 0
Significant Unobservable Inputs, Level 3 | Government-sponsored enterprises |  |
Assets [Abstract] |  |
Marketable securities | 0 |
Significant Unobservable Inputs, Level 3 | U.S Treasury securities |  |
Assets [Abstract] |  |
Marketable securities |  | 0
Significant Unobservable Inputs, Level 3 | Corporate debt securities |  |
Assets [Abstract] |  |
Marketable securities |  | 0
Securities | $ 0 |
Significant Unobservable Inputs, Level 3 | Common stock warrants |  |
Assets [Abstract] |  |
Common stock warrants |  | $ 1,890

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