Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Current assets
Allowance for doubtful accounts receivable	$ 4,568	$ 4,708
Stockholders' equity
Preferred stock, par value	$ 100	$ 100
Preferred stock, shares authorized	750	750
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	500,000	500,000
Common stock, shares issued	32,338	32,338
Treasury stock, shares	5,139	5,285