Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,069	$ 658
Unamortized discount, current maturities	699	329
Unamortized discount, noncurrent maturities	$ 1,969	$ 1,113
Common Stock
Par value (in USD per share)	$ 0.0001	$ 0.0001
Shares authorized (in shares)	50,000,000	50,000,000
Shares issued (in shares)	20,768,401	17,785,288
Shares outstanding (in shares)	20,768,401	17,785,288