CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)
Dec. 31, 2014
Dec. 31, 2013
CONSOLIDATED BALANCE SHEETS    
Preferred stock, par value (in dollars per share) $ 0.01 $ 0.01
Preferred stock, shares authorized 100,000,000 100,000,000
Preferred stock, shares issued 0 0
Common stock, par value (in dollars per share) $ 0.01 $ 0.01
Common stock, shares authorized 750,000,000 750,000,000
Common stock, shares issued 109,669,429 109,653,363
Common stock, shares outstanding 109,669,429 109,653,363