Commitments and Contingencies - Narrative (Details) - USD ($)	1 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Purchase obligations due within next twelve months			$ 1,500,000
Operating lease relating to future lease commitments			1,200,000
Operating lease relating to future lease commitments due within the next twelve months			$ 849,000
Scenario Forecast
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Operating lease end date	2019-07
Operating lease termination notice period	9 months
San Diego, California | Research and Development centre | Subsequent Event
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Operating lease expiration date		2020-07
Primary facility lease | Sunnyvale, California
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Operating lease expiration date			2020-03
Wafer and finished goods inventory
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Outstanding commitment for purchases			$ 25,000	$ 1,100,000
Other goods and services
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Total outstanding purchase obligations			$ 1,800,000