CONDENSED CONSOLIDATED BALANCE SHEETS - (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 30, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Allowance for Accounts receivable	$ 236	$ 139
Accumulated depreciation	$ 184,364	$ 191,988
Preferred stock, without par value	$ 0	$ 0
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Common stock, without par value	$ 0	$ 0
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	56,079,128	55,808,008
Cost of common stock held in treasury, shares	22,276,742	22,249,144