Capital Stock	12 Months Ended
Dec. 31, 2017
Equity [Abstract]
Capital Stock	Capital Stock Warrants No warrants which were exercisable for common stock were exercised during 2017, 2016 or 2015. On September 28, 2017, warrants to purchase 72,727 shares of common stock, at an exercise price of $8.25 per share, expired. No warrants were outstanding as of December 31, 2017. Public Offering In April 2017, we completed a public offering in which we issued and sold 6.3 million shares of our common stock, par value $0.0001 per share, at a public offering price of $4.00 per share. We received net proceeds of approximately $23.2 million after deducting the underwriting discounts, commissions and other offering expenses of $0.6 million.

Capital Stock

12 Months Ended

Dec. 31, 2017

Warrants

No warrants which were exercisable for common stock were exercised during 2017, 2016 or 2015. On September 28, 2017, warrants to purchase 72,727 shares of common stock, at an exercise price of $8.25 per share, expired. No warrants were outstanding as of December 31, 2017.

Public Offering

In April 2017, we completed a public offering in which we issued and sold 6.3 million shares of our common stock, par value $0.0001 per share, at a public offering price of $4.00 per share. We received net proceeds of approximately $23.2 million after deducting the underwriting discounts, commissions and other offering expenses of $0.6 million.