Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Oct. 01, 2017	Dec. 31, 2016
Trade accounts receivable, allowance for doubtful accounts	$ 4,760	$ 5,056
Preferred stock, par value	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	1,000,000	1,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common Stock, Shares Authorized	29,000,000	29,000,000
Common Stock, Shares, Issued	16,500,540	16,445,363
Common Stock, Shares, Outstanding	16,500,540	16,445,363