Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Current assets:
Allowance for doubtful accounts	$ 714	$ 884
Shareholders' equity:
Undesignated preferred stock, shares authorized (in shares)	5,000	5,000
Undesignated preferred stock, shares issued (in shares)	0	0
Undesignated preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	142,500	142,500
Common stock, shares issued (in shares)	38,813	43,569
Common stock, shares outstanding (in shares)	38,813	43,569