Net Income (Loss) Per Share - Summary of Common Stock Issuance (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Sep. 10, 2019	Jun. 04, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share)			$ 0.01		$ 0.01		$ 0.01
Net proceeds			$ 73,781	$ 0	$ 122,668	$ 0
First Offering
Subsidiary, Sale of Stock [Line Items]
Aggregate net proceeds from stock offering		$ 50,000
Common stock, par value (in dollars per share)		$ 0.01
Shares sold in offering		16,630,444
Par value, common stock (in dollars per share)		$ 3.00
Net proceeds		$ 48,900
Second Offering
Subsidiary, Sale of Stock [Line Items]
Aggregate net proceeds from stock offering	$ 75,000
Common stock, par value (in dollars per share)	$ 0.01
Shares sold in offering	14,219,677
Par value, common stock (in dollars per share)	$ 5.27
Net proceeds	$ 73,800