Common Stock Issuance (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) shares
Cash received from stock sale, before issuance costs	$ 1,168,000
Registered January 2019
Number of shares of common stock issued | shares	2,000,000
Cash received from stock sale, before issuance costs	$ 1,200,000
Stock issuance costs	$ 26,000
Terms and provisions	In January 2019, we raised $1.2 million before issuance costs of approximately $26,000 through a registered direct offering of 2.0 million shares of our common stock to Shehnee Lawrence Farhi.
Public December 2018
Number of shares of common stock issued | shares	7,000,000
Cash received from stock sale, before issuance costs	$ 4,200,000
Stock issuance costs	$ 524,000
Terms and provisions	In December 2018, we raised $4.2 million before issuance costs of approximately $524,000 through an underwritten public offering of 7.0 million shares of our common stock.
Public June 2018
Number of shares of common stock issued | shares	14,400,000
Cash received from stock sale, before issuance costs	$ 18,000,000
Stock issuance costs	$ 1,400,000
Terms and provisions	In June 2018, we raised $18.0 million before issuance costs of approximately $1.4 million through an underwritten public offering of 14.4 million shares of our common stock.