Stock-based Awards (Details - Options) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Additional disclosure
Stock-based compensation expense	$ 8,635	$ 9,097
Options
Number of Options
Outstanding at the beginning of period (in shares)	14,114,651
Granted (in shares)	1,307,779
Exercised (in shares)	(345,913)
Canceled/forfeited (in shares)	(1,111,221)
Outstanding at the end of the period (in shares)	13,965,296		14,114,651
Weighted-Average Exercise Price
Outstanding at the beginning of period (in dollars per share)	$ 12.32
Granted (in dollars per share)	7.61
Exercised (in dollars per share)	8.11
Canceled/forfeited (in dollars per share)	13.30
Outstanding at the end of the period (in dollars per share)	$ 11.91		$ 12.32
Additional disclosure
Weighted average remaining contractual life (in years)	7 years		7 years
Remaining stock-based compensation expense for unvested awards	$ 32,100
Weighted average period over which remaining stock based compensation expense for unvested awards is expected to be recognized	2 years 5 months 23 days
Stock-based compensation expense	$ 3,100	$ 4,600