Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Accounts receivable, allowance for doubtful accounts	$ 8,580	$ 7,791
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	142,977,896	141,656,426
Common stock, shares outstanding	142,977,896	141,656,426