Concentration of Credit Risk and Significant Customers (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2020

Dec. 31, 2019

Risks and Uncertainties [Abstract]

Schedules of concentration of risk, by risk factor

Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following table:

	Revenue for the Three Months Ended March 31,		Accounts Receivable As of
	2020	2019	March 31, 2020	December 31, 2019
Customer A	*	30.6%	*	*
Customer B	*	20.1%	*	*
Customer C	31.3%	*	53.3%	60.0%
Customer D	53.2%	32.3%	32.3%	20.4%

* Less than 10% of total

Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following:

	Revenue for the Year Ended December 31,		Accounts Receivable As of December 31,
	2019	2018	2019	2018
Customer A	*	44.0%	*	22.7%
Customer B	*	17.6%	*	43.7%
Customer C	*	16.0%	*	*
Customer D	79.6%	*	60.0%	19.3%
Customer E	13.3%	*	20.4%	*

* Less than 10% of total