Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary Of Significant Accounting Policies [Line Items]
Unrealized loss on short-term investments	$ (7,000)	$ 0	$ (7,000)	$ 0
Maximum
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents maturity period			90 days
Short-term investments maturity period			1 year
Minimum
Summary Of Significant Accounting Policies [Line Items]
Short-term investments maturity period			90 days