Derivative Liabilities - Fair value assumptions, derivative additional investment rights liability (Details)	1 Months Ended	6 Months Ended
	Jul. 31, 2016 $ / shares	Jan. 31, 2017 $ / shares shares
Notes to Financial Statements
Underlying number of units of convertible preferred stock | shares		500
Underlying number of units of warrants | shares		33,333
Current exercise price of warrants	$ 20.00	$ 15.00
Current conversion price of preferred stock		$ 15.00
Time to expiration		18 days
Risk-free interest rate		0.0038
Estimated volatility		0.13
Dividend		0.00%
Stock price at period end date	$ 10.00	$ 8.00