Stock-based Awards (Details - Options) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Additional disclosure
Stock-based compensation expense	$ 6,177	$ 8,635
Options
Number of Options
Outstanding at the beginning of period (in shares)	10,625,980
Granted (in shares)	1,713,111
Exercised (in shares)	(3,166)
Canceled/forfeited (in shares)	(284,405)
Outstanding at the end of the period (in shares)	12,051,520		10,625,980
Weighted-Average Exercise Price
Outstanding at the beginning of period (in dollars per share)	$ 11.22
Granted (in dollars per share)	2.66
Exercised (in dollars per share)	0.83
Canceled/forfeited (in dollars per share)	12.04
Outstanding at the end of the period (in dollars per share)	$ 9.99		$ 11.22
Additional disclosure
Weighted average remaining contractual life (in years)	5 years 7 months 6 days		5 years 2 months 12 days
Remaining stock-based compensation expense for unvested awards	$ 12,500
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized	2 years 4 months 24 days
Stock-based compensation expense	$ 1,600	$ 3,100