Stockholders' Equity - Preferred Stock and Common Stock Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Jun. 30, 2018 USD ($) shares	Dec. 31, 2018 vote $ / shares shares	Dec. 31, 2017 $ / shares shares
Subsidiary, Sale of Stock [Line Items]
Preferred stock authorized (shares)		10,000,000	10,000,000
Preferred stock par value (in usd per share) | $ / shares		$ 0.001	$ 0.001
Preferred stock outstanding (shares)		0	0
Preferred stock issued (shares)		0	0
Common stock authorized (shares)		50,000,000	50,000,000
Common stock, par value (in usd per share) | $ / shares		$ 0.001	$ 0.001
Number of votes entitled to for each common share held | vote		1
Common stock issued (shares)		42,078,164	34,807,509
Common stock outstanding (shares)		42,078,164	34,807,509
Public Stock Offering [Member]
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock, net of offering costs (shares)	740,417
Proceeds from sale of stock | $	$ 30.3