Stockholders' Equity - Pre-2017 Non-Qualified Stock Options, Additional Information (Details) - Pre-2017 non-qualified stock options - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	2,465,500		2,500,500
Options granted (in shares)	0
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 1	$ 115

Amount of noncash expense for share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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