Description of Business - Additional Information (Details) $ in Thousands	1 Months Ended				9 Months Ended
	Mar. 31, 2019 USD ($) shares	Oct. 31, 2018	Jul. 31, 2018 USD ($) shares	Jan. 31, 2018 USD ($) shares	Sep. 30, 2019 USD ($) platform	Sep. 30, 2018 USD ($)
Subsidiary, Sale of Stock [Line Items]
Number of platforms | platform					2
Proceeds from sale of common stock, net | $					$ 68,273	$ 53,847
At The Market Equity Offering
Subsidiary, Sale of Stock [Line Items]
Shares sold in offering | shares				0
Proceeds from sale of common stock, net | $				$ 40,000
Public Stock Offering
Subsidiary, Sale of Stock [Line Items]
Shares sold in offering | shares	3,175,000		4,600,000
Total gross proceeds from stock offering | $	$ 73,000		$ 57,500
Aggregate net proceeds from stock offering | $	$ 68,300		$ 53,800
Selling Stockholder [Member]
Subsidiary, Sale of Stock [Line Items]
Shares sold in offering | shares	2,000,000
Over-Allotment Option [Member]
Subsidiary, Sale of Stock [Line Items]
Shares sold in offering | shares	675,000		600,000
Term Loan Agreement
Subsidiary, Sale of Stock [Line Items]
Debt Instrument, Redemption Price, Percentage		4.00%
Upfront Fee Of Aggregate Principal Amount, Percentage		0.50%