Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Property and equipment, gross	$ 377	$ 1,976
Less accumulated depreciation and amortization	(321)	(1,655)
Total property and equipment, net	56	321
Depreciation and amortization expense	$ 119	304
Lab equipment
Property and Equipment
Property and equipment, gross		$ 1,470
Estimated Useful Life	3 years	3 years
Computer equipment
Property and Equipment
Property and equipment, gross	$ 100	$ 165
Estimated Useful Life	3 years	3 years
Furniture and fixtures
Property and Equipment
Property and equipment, gross	$ 75	$ 77
Estimated Useful Life	5 years	5 years
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 202	$ 264

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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