Stock-Based Compensation - Service Based Stock Options - Others (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expenses	$ 433	$ (1,461)	$ 197	$ (526)
Stock option awards - service based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			1,522,162	1,610,344
Forfeited (in shares)			277,764	211,471
Expirations (in shares)			1,266,553	3,983,335
Stock based compensation expenses	344	$ 336	$ 735	$ 776
Unrecognized stock-based compensation expenses	$ 2,000		$ 2,000
Unrecognized stock-based compensation expense, weighted average remaining term (in years)			3 years

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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