Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	57,139,755	56,778,718
Common stock, shares outstanding	55,837,912	55,577,667
Treasury stock, shares	1,301,843	1,201,051