Quarterly report pursuant to Section 13 or 15(d)

Recent Accounting Pronouncements - Cash flow changes, reconciliation of components of cash (Details)

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Recent Accounting Pronouncements - Cash flow changes, reconciliation of components of cash (Details)
$ in Millions
1 Months Ended
Aug. 31, 2016
item
Jun. 30, 2018
USD ($)
Dec. 31, 2017
USD ($)
Jun. 30, 2017
USD ($)
Dec. 31, 2016
USD ($)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]          
Cash and cash equivalents   $ 485 $ 1,029    
Restricted cash included in other current assets   55 8    
Restricted cash included in other assets   23 10    
Total cash and cash equivalents and restricted cash at end of period   $ 563 $ 1,047 $ 754 $ 572
Number of cash flow issues the FASB guidance addresses | item 8