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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of assets held-for-sale that are not part of a disposal group, expected to be sold within a year or the normal operating cycle, if longer.

+ References

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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.

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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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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.

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- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

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Property and equipment (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
Property and equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jan. 31, 2017	Dec. 31, 2016
Property and equipment
Property and equipment, gross	$ 7,873	$ 7,873		$ 7,873			$ 9,000
Less: accumulated depreciation	(3,917)	(3,917)		(3,917)			(3,428)
Property and equipment, net	3,956	3,956		3,956			5,572
Depreciation and amortization expense		500	$ 600	951	$ 1,067
Fixed assets held-for-sale	500	500		500		$ 500
Impairment charge	300
Laboratory equipment
Property and equipment
Property and equipment, gross	4,136	4,136		4,136			5,184
Furniture
Property and equipment
Property and equipment, gross	775	775		775			793
Computer equipment
Property and equipment
Property and equipment, gross	208	208		208			208
Leasehold improvements
Property and equipment
Property and equipment, gross	$ 2,754	$ 2,754		$ 2,754			$ 2,815