Condensed Consolidated Statements of Operations (Parenthetical) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Income Statement [Abstract]        
Income tax benefit $ 0 $ 0 $ 0 $ 0