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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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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