Risks and Liquidity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Risks and Liquidity
Accumulated deficit	$ (204,789)	$ (196,653)

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant