Segment Information and Foreign Operations - Concentration of Credit Risk (Details) - customer	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenues
Revenue, Major Customer [Line Items]
Number of customers representing significant share	2
Accounts Receivable
Revenue, Major Customer [Line Items]
Number of customers representing significant share	3		3
Landmark | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	17.00%	11.00%
Haisi Optoelectronics | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers		12.00%
Osram Opto [Member] | Revenues
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	15.00%
Major Customer One | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	20.00%		14.00%
Major Customer Two | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	13.00%		13.00%
Major Customer Three | Accounts Receivable
Revenue, Major Customer [Line Items]
Percentage share generated by major customers	12.00%		12.00%
Top Five Major Customers | Revenues
Revenue, Major Customer [Line Items]
Number of customers representing significant share	5	5
Percentage share generated by major customers	49.00%	40.00%