Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Jan. 31, 2019	Apr. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Common stock, par value			$ 0.001	$ 0.001
Follow-On Public Offering [Member]
Subsequent Event [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		553,825
Proceeds from issuance of common stock		$ 9.9
Follow-On Public Offering [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares	2,645,000
Common stock, par value	$ 55.25
Proceeds from issuance of common stock	$ 139.7
Underwriter Purchase Option [Member]
Subsequent Event [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		26,825
Underwriter Purchase Option [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares	345,000