Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Details)

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Basis of Presentation (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2017
Jun. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Gain (loss) on dispositions, net (note 1)   $ (18) $ (18)
Buy Seasons | Disposed of by Sale      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Gain (loss) on dispositions, net (note 1) $ (18)    
Disposal Group Revenue   7 13
Disposal Group Net Earnings Loss     $ 1
Buy Seasons | Disposed of by Sale | Maximum      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Disposal Group Net Earnings Loss   $ 1