Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments (Cash and Cash Equivalents Fair Value Measurements) (Details)

v3.8.0.1
Financial Instruments (Cash and Cash Equivalents Fair Value Measurements) (Details) - USD ($)
$ in Millions
Sep. 30, 2017
Dec. 31, 2016
Schedule of Investments [Line Items]    
Cash and cash equivalents $ 879 $ 1,264
Fair Value, Inputs, Level 1 [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents 115 50
Fair Value, Inputs, Level 2 [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents 646 1,147
Cash [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents 118 67
Money Market Funds [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents 115 50
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]    
Schedule of Investments [Line Items]    
Cash and cash equivalents $ 646 $ 1,147