Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Condensed Consolidated Balance Sheets
Trade receivables, allowances	$ 2,563	$ 4,021
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000	15,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	250,000	250,000
Common stock, shares issued	68,459	66,542
Treasury stock, shares	25,894	24,823