CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)
In Millions, except Share data, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Maximum allowance for accounts receivable, customer (less than $1 million) $ 1 $ 1
Other receivables, allowance (in dollars) $ 1 $ 1
Preferred stock, par value (in dollars per share) $ 0.01 $ 0.01
Preferred stock, shares authorized 50,000,000 50,000,000
Preferred stock, shares issued 0 0
Preferred stock, shares outstanding 0 0
Class A    
Common shares, par value (in dollars per share) $ 0.01 $ 0.01
Common shares, shares authorized 550,000,000 550,000,000
Common shares, shares issued 248,000,000 245,000,000
Common shares, shares outstanding 248,000,000 245,000,000
Class B    
Common shares, par value (in dollars per share) $ 0.01 $ 0.01
Common shares, shares authorized 800,000 800,000
Common shares, shares issued 800,000 800,000
Common shares, shares outstanding 800,000 800,000