Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Common Stock
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Shares Issued	269,967,577	269,323,084
Common Stock, Shares Authorized	640,000,000	640,000,000
Treasury Stock
Common Stock Held in Treasury, Shares	386,828	303,633