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Stock-based Compensation Expense - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 10,200,000		$ 10,200,000
Unrecognized stock-based compensation expense, weighted average period expect to recognized			3 years 1 month 9 days
Grants Under the 2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock that authorized for issuance	3,566,428		3,566,428		3,209,285
Weighted average grant date fair value	$ 7.75	$ 3.46	$ 5.74	$ 3.46
Aggregate intrinsic value of stock options exercised	$ 200,000	$ 0	$ 200,000	$ 0
Grants Outside the 2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value of restricted stock awards vested	$ 1,000,000		$ 2,400,000