PARENTHETICAL DATA TO CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets
Allowance for doubtful accounts	$ 22,719	$ 22,728
Stockholders' equity
Preferred stock, par value	$ 0.00	$ 0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.00	$ 0.00
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	59,115,499	57,800,791
Common stock, shares outstanding	56,534,396	55,109,038
Treasury stock, shares at cost	2,582,520	2,638,421