Condensed Consolidated Balance Sheets (Parenthetical) (USD $)
Dec. 31, 2014
Dec. 31, 2013
Statement of Financial Position [Abstract]    
Common stock, par value per share (in dollars per share) $ 0.01 $ 0.01
Common stock, shares issued (in shares) 411,824,039 370,570,565
Common stock, shares outstanding (in shares) 411,350,440 370,363,803