Significant Balance Sheet Components - Accounts Receivable, Net (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable, Net
Allowance for doubtful accounts	$ (412,000)	$ (412,000)
Accounts receivable, net	37,694,000	58,815,000
Billed
Accounts Receivable, Net
Accounts receivable	35,940,000	57,184,000
Unbilled
Accounts Receivable, Net
Accounts receivable	$ 2,166,000	$ 2,043,000