Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Current Assets:
Allowances for accounts receivable	$ 16,100	$ 15,500
Stockholders' equity:
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	125,000	125,000
Common stock, share issued	54,003	53,464
Common stock, shares outstanding	54,003	53,464