Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	66,687,994	66,601,909
Common stock, held in treasury	69,816	69,816