Convertible Preferred Stock and Stockholders' Equity (Details 3) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Number of Restricted Stock Units
Balance at the beginning of the period | shares	525,250
Canceled | shares	(75,000)
Balance at the end of the period | shares	450,250
Weighted-Average Grant Date Fair Value per Share
Balance at the beginning of the period | $ / shares	$ 4.89
Canceled | $ / shares	4.89
Balance at the end of the period | $ / shares	$ 4.89