Weighted Average Shares Outstanding and Net Loss Per Share - Summary of Reconciliation of Weighted Average Shares Outstanding Used in Calculating Basic and Diluted Net Loss Per Share (Parenthetical) (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Antidilutive shares excluded from calculating diluted net loss per share	502,000	673,000