Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Current assets
Allowance for doubtful accounts receivable	$ 5,094	$ 4,708
Stockholders' equity
Preferred stock, par value	$ 100	$ 100
Preferred stock, shares authorized	750,000	750,000
Preferred stock, shares issued
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	32,338,000	32,338,000
Treasury stock, shares	5,098,000	5,285,000