Warrants (Narrative) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands

1 Months Ended

12 Months Ended

Mar. 31, 2014

Feb. 28, 2014

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Warrants Narrative Details

Common shares underlying warrants

3,761

5,039

6,526

8,091

Warrant exercise price, per share

$ 2.23

$ 3.34

$ 3.08

Loss on warrant exchange

$ 0

$ 0

$ (4,967)

Warrant Transactions Connected with Contingently Convertible Securities

The warrants to purchase 2.1 million shares of our common stock that we sold in our March 2014 offering have an exercise price of $2.47 per share and expire on the fifth anniversary of the date of issuance.

In February 2014, we issued 3.7 million shares of our common stock under the exchange provision of our then-outstanding warrants. We did not receive additional cash consideration in the exchange transaction. We recorded a loss of $5.0 million during the year ended December 31, 2014 on the exchange, as the fair market value of the common stock issued was greater than the obligation recorded due to the increase in stock price from December 31, 2013 to the date the warrants were exchanged.