Inventory (Details) - USD ($) $ in Thousands	4 Months Ended	12 Months Ended
Apr. 28, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials		$ 4,961	$ 3,852
Work in process		490	313
Finished goods		759	201
Total inventories		6,210	4,366
Research and development	$ 1,600	99,911	$ 83,076	$ 107,406
Costs not yet absorbed to goods sold to customers		$ 100
Finished goods shelf life		36 months

Costs Not Yet Absorbed to Goods Sold to Customers

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Inventory, Finished Goods, Shelf Life

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- Definition

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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