Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 2,654	$ 2,370
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	13,760,000	13,533,000
Common stock, shares outstanding (in shares)	13,760,000	13,533,000