Quarterly report pursuant to Section 13 or 15(d)

CONSOLIDATED BALANCE SHEETS (Parenthetical)

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CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares
shares in Millions
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Dec. 31, 2016
Treasury stock, shares 1 1    
Class A common stock        
Common stock, shares issued 174 173 180 180
Class B common stock        
Common stock, shares issued 689 687 689 689