Investments in Privately-Held Companies - Minority Investment Entities (Details) - Five Minority Investments - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Net revenue	$ 3,713,000	$ 8,017,000	$ 14,713,000	$ 24,366,000
Gross profit (loss)	309,000	2,141,000	1,423,000	5,477,000
Operating (loss)	(436,000)	631,000	(1,857,000)	767,000
Net (loss)	(502,000)	315,000	(2,518,000)	(422,000)
Minority investment entities
Entity (loss) excluding impairment	$ (200,000)	$ 6,000	$ (1,800,000)	$ (21,000)