Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 456	$ 456
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,980,000	1,980,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	8,979,500	7,550,642
Treasury stock at cost, common shares held	292,855	292,855