Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Consolidated Balance Sheets
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued
Junior participating preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Junior participating preferred stock, shares authorized	250,000	250,000	250,000
Junior participating preferred stock, shares issued
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000	210,000,000
Common stock, shares issued	61,271,603	61,108,184	60,656,360
Treasury stock, shares	26,359