Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Marketable securities, restricted securities	$ 54	$ 0
Accounts receivable, net of reserves	5,778	4,555
Marketable securities, restricted securities	$ 44	$ 42
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares designated as Series A Junior Participating Preferred Stock (in shares)	700,000	700,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	700,000,000	700,000,000
Common stock, shares issued (in shares)	198,954,007	195,561,243
Common stock, shares outstanding (in shares)	177,331,901	177,504,624
Treasury stock, shares (in shares)	21,622,106	18,056,619