Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Oct. 17, 2017	Jul. 13, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 13, 2017
Equity [Abstract]
Common stock, shares authorized (in shares)			500,000,000	17,214,000		60,000,000
Common stock, par value (in dollars per share)			$ 0.001	$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)			10,000,000	0		11,520,698
Preferred stock, par value (in dollars per share)			$ 0.001	$ 0.001		$ 0.001
Common stock, shares issued (in shares)			23,791,392	2,651,000
Common stock, shares outstanding (in shares)			23,791,392	2,651,000
Class of Stock [Line Items]
Repurchase of shares (in shares)			0	1,457	0
Stock issued during period (in shares)	3,000,000
Shares issued (in dollars per share)	$ 68.50
Series D convertible preferred stock
Class of Stock [Line Items]
Stock issued during period (in shares)		5,490,973
Shares issued (in dollars per share)		$ 7.42
Net proceeds from stock issued		$ 40.7
Common Stock
Class of Stock [Line Items]
Warrants exercised, number of shares represented (as shares)			477,908
Warrants exercised, number of shares represented, cashless exercise (as shares)			359,999
Shares issued as a result of warrants exercised (in shares)			398,837
Repurchase of shares (in shares)				2,000
Stock issued during period (in shares)			9,021,000