Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,478	$ 1,405
Unamortized discount, current	1,024	1,109
Unamortized discount, noncurrent	$ 7,333	$ 2,381
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	25,261,093	21,489,112
Common stock, shares outstanding (in shares)	25,261,093	21,489,112