Basic and Diluted Net Income (Loss) Per Common Share - Summary of Calculated Net Income (Loss) Per Share (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Class A common stock
Basic net income (loss) per share allocated to stockholders:
Basic net income (loss) per share allocated to stockholders	$ (0.27)	$ 0.35	$ (0.73)	$ (1.14)
Class B common stock
Basic net income (loss) per share allocated to stockholders:
Basic net income (loss) per share allocated to stockholders	(0.27)	0.35	(0.73)	(1.14)
Series C convertible preferred stock
Basic net income (loss) per share allocated to stockholders:
Basic net income (loss) per share allocated to stockholders	$ (0.27)	$ 0.35	$ (0.73)	$ (1.14)