Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Statement of Financial Position [Abstract]
Marketable securities, restricted securities	$ 51	$ 272
Accounts receivable, net of reserves	4,914	5,232
Marketable securities, restricted securities	$ 45	$ 45
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares designated as Series A Junior Participating Preferred Stock	700,000	700,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	700,000,000	700,000,000
Common stock, shares issued	194,324,558	192,383,121
Common stock, shares outstanding	185,981,780	186,603,380
Treasury stock, shares	8,342,778	5,779,741