Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Condensed Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	57,104,489	56,778,718
Common stock, shares outstanding	55,842,938	55,577,667
Treasury stock, shares	1,261,551	1,201,051