Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Apr. 01, 2012	Dec. 31, 2011
Assets:
Allowance for doubtful accounts	$ 5,727	$ 5,553
Accumulated depreciation	$ 111,101	$ 106,760
Shareholders' Equity:
Preferred stock, shares authorized	500	500
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	70,000	70,000
Common stock, shares issued	37,935	37,866
Common stock, shares outstanding	37,935	37,866
Common stock, par value	$ 0.00	$ 0.00