Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Marketable securities, restricted securities	$ 56	$ 0
Accounts receivable, net of reserves	5,445	4,555
Marketable securities, restricted securities	$ 44	$ 42
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	197,322,448	179,042,608
Common stock, shares outstanding	195,561,243	177,504,624
Treasury stock, shares	18,279,840	18,056,619