Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Accounts receivable, allowance for doubtful accounts	$ 23	$ 33
Shareholders' Equity:
Common stock, shares authorized (in shares)	480,000,000	480,000,000
Common stock, shares, issued (in shares)	128,970,776	122,904,368
Common stock, shares outstanding (in shares)	128,970,776	122,904,368