Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 25, 2014	Dec. 25, 2013
Assets [Abstract]
Accumulated depreciation	$ 252,475	$ 255,966
Shareholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	135,000	135,000
Common stock, shares issued	105,229	105,014
Common stock, shares outstanding	85,803	89,232
Treasury stock, at cost, shares	19,426	15,782