Equity, Stock Options (Details)	12 Months Ended
	Dec. 31, 2018 shares
2017 Employee Option Plan
Stock-Based Compensation
Common Stock reserved for issuance	30,000,000
Shares available for the granting of additional stock options	16,985,620
Options ratable vesting period	5 years
Options exercisable period	10 years
2009 Employee Option Plan
Stock-Based Compensation
Number of additional stock options that will be granted (in shares)	0
Options ratable vesting period	5 years
Options exercisable period	10 years
2004 Directors Option Plan
Stock-Based Compensation
Options exercisable period	10 years