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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

Name:	us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Subsequent Events (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		24 Months Ended
Subsequent Events (Details) - USD ($)	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2019
Subsequent events
Research and development expense		$ 6,453,000	$ 6,420,000	$ 19,706,000	$ 19,236,000
Global Foundries \| Joint Development Agreement
Subsequent events
Research and development expense		$ 1,600,000	$ 850,000	$ 5,900,000	$ 4,100,000
Subsequent Events \| Global Foundries \| Joint Development Agreement
Subsequent events
Additional extension related to an SOW that extends beyond the extended term	3 months
Subsequent Events \| Global Foundries \| Joint Development Agreement \| Forecast \| Maximum
Subsequent events
Research and development expense						$ 5,800,000