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Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Common stock, par value (usd per share) $ 0.01 $ 0.01  
Treasury stock, par value (usd per share) 0.01 0.01  
Common stock      
Common stock, par value (usd per share) 0.01 0.01 $ 0.01
Treasury stock      
Treasury stock, par value (usd per share) $ 0.01 $ 0.01 $ 0.01