Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 27, 2015	Dec. 31, 2014
Current assets:
Accounts receivable allowance for doubtful accounts	$ 557	$ 669
Stockholders' equity:
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	79,595,000	78,267,000
Common stock, shares outstanding (in shares)	75,213,000	74,009,000
Treasury stock, shares (in shares)	4,382,000	4,258,000