CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Receivables, allowance for doubtful accounts	$ 5,486	$ 5,860
Preferred stock, Authorized shares	5,000,000	5,000,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, Issued
Common stock, Authorized shares	150,000,000	150,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, Issued shares	87,083,550	85,968,630
Treasury stock, shares	3,654,044	2,734,747