Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Condensed Consolidated Balance Sheets
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Preferred stock, authorized	5,000,000	5,000,000	5,000,000
Preferred stock, issued	0	0	0
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, authorized	300,000,000	300,000,000	300,000,000
Common stock, issued	37,068,904	37,068,904	54,068,904
Treasury stock, shares	10,045,948	7,075,563	20,478,818