Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Sep. 30, 2011	Dec. 31, 2010
Current assets:
Allowance for doubtful accounts	$ 15,437	$ 12,314
Equity:
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	500	500
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	180,000	180,000
Common stock, shares issued (in shares)	106,481	115,499
Common stock, shares outstanding (in shares)	106,481	115,499