Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Marketable securities, restricted securities	$ 0	$ 272
Accounts receivable, net of reserves	4,555	5,232
Marketable securities, restricted securities	$ 42	$ 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	195,561,243	192,383,121
Common stock, shares outstanding	177,504,624	186,603,380
Treasury stock, shares	18,056,619	5,779,741