Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000,000	500,000,000,000
Common Stock, Shares, Issued	145,799,929	134,966,740
Treasury Stock, Shares	9,337,865	11,611,093