Balance Sheet Components - Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Apr. 30, 2020	Dec. 31, 2019	Apr. 30, 2019	Aug. 31, 2017	Aug. 08, 2017
Balance Sheet Components [Line Items]
Common stock, shares issued		85,281,000		78,005,000
Amortization of debt discount and issuance cost	$ 336	$ 149
Noncurrent assets		12,156		$ 12,476
Convertible Notes
Balance Sheet Components [Line Items]
Debt discount			$ 8,600
Evercord
Balance Sheet Components [Line Items]
Net collections		2,000
Credit loss expense		1,200
Evercord | Contingent consideration
Balance Sheet Components [Line Items]
Total consideration				$ 4,700
Noncurrent assets
Balance Sheet Components [Line Items]
Debt discount		0
Long-term Debt
Balance Sheet Components [Line Items]
Debt discount		900
2017 Term Loan
Balance Sheet Components [Line Items]
Common stock, shares issued					25,000	300,000
Remaining borrowing capacity		50,000				$ 50,000	$ 25,000
2017 Term Loan | Noncurrent assets
Balance Sheet Components [Line Items]
Debt instrument, fee amount						$ 1,200
Evercord | Contingent consideration
Balance Sheet Components [Line Items]
Accounts receivable		1,500
BGI Genomics | Sequencing products and services
Balance Sheet Components [Line Items]
Noncurrent assets	$ 10,000	$ 10,000