Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	162,500,000	162,500,000
Common stock, shares issued	62,263,963	62,263,963
Treasury stock, shares	4,407,038	4,429,184
Participating Convertible Preferred Stock-Series D [Member]
Participating convertible preferred stock, par value	$ 0.01	$ 0.01
Participating convertible preferred stock, shares authorized	200,000	200,000
Participating convertible preferred stock, shares issued	109,239	109,239