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Borrowings and Lines of Credit (Long-term Debt Obligations) (Details) € in Millions, $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Long-term debt		$ 4,299				$ 4,123		$ 4,299
Capital lease obligations		18				15		18
Long-term debt and capital lease obligations		4,317				4,138		4,317
Less payments due within one year		530				4		530
Long-term debt		$ 3,787	$ 3,817	$ 3,998	$ 4,089	$ 4,134		$ 3,787
Effective interest rates		8.40%				8.40%		8.40%
Repayments of debt			$ 7	$ 8	$ 9	$ 588		$ 379	$ 340
Proceeds from notes payable		$ 987						1,240
Notional amount of non-derivative instruments \| €							€ 300
Notes 6.875 Percent Due 2017
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						6.875%
Notes 3.875 Percent Due 2015
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						3.875%
Notes 1.9 Percent Due 2016
Debt Instrument [Line Items]
Notional amount of non-derivative instruments	$ 250
Debt instrument, interest rate, stated percentage	1.90%					1.90%
3-year Variable Rate Euro Bank Loan Due 2017
Debt Instrument [Line Items]
Long-term debt		526				$ 0		526
Repayments of debt						587
Notional amount of non-derivative instruments \| €							500
Notes 0.00% Due 2019
Debt Instrument [Line Items]
Long-term debt		313				$ 358		313
Notional amount of non-derivative instruments \| €							300
Debt instrument, interest rate, stated percentage						0.00%
Notes 2.3 Percent Due 2019
Debt Instrument [Line Items]
Long-term debt		298				$ 299		298
Debt instrument, interest rate, stated percentage						2.30%
Notes 3.6 Percent Due 2020
Debt Instrument [Line Items]
Long-term debt		496				$ 497		496
Debt instrument, interest rate, stated percentage						3.60%
Non-callable Debentures 9 Percent Due 2021
Debt Instrument [Line Items]
Long-term debt		133				$ 133		133
Debt instrument, interest rate, stated percentage						9.00%
Notes 0.875 Percent Due 2022
Debt Instrument [Line Items]
Long-term debt		626				$ 716		626
Notional amount of non-derivative instruments \| €							600
Debt instrument, interest rate, stated percentage						0.875%
Notes 0.875% Due 2025
Debt Instrument [Line Items]
Long-term debt		621				$ 710		621
Notional amount of non-derivative instruments \| €							600
Debt instrument, interest rate, stated percentage						0.875%
Notes 1.4 Percent Due 2027
Debt Instrument [Line Items]
Long-term debt		620				$ 711		620
Debt instrument, interest rate, stated percentage						1.40%
Notes 2.5 Percent Due 2029
Debt Instrument [Line Items]
Long-term debt		83				$ 95		83
Notional amount of non-derivative instruments \| €							80
Debt instrument, interest rate, stated percentage						2.50%
Notes 7.70 Percent Due 2038
Debt Instrument [Line Items]
Long-term debt		174				$ 174		174
Debt instrument, interest rate, stated percentage						7.70%
Notes 5.5 Percent Due 2040
Debt Instrument [Line Items]
Long-term debt		247				$ 247		247
Debt instrument, interest rate, stated percentage						5.50%
Notes 3.0 Percent Due 2044
Debt Instrument [Line Items]
Long-term debt		118				$ 137		118
Notional amount of non-derivative instruments \| €							€ 120
Debt instrument, interest rate, stated percentage						3.00%
Impact Of Derivatives On Debt
Debt Instrument [Line Items]
Long-term debt		3				$ 3		3
Other Non US Debt
Debt Instrument [Line Items]
Long-term debt		$ 41				$ 43		$ 41
Long-term debt, percentage bearing variable interest, percentage rate		3.80%				3.70%		3.80%
Notes 6.65 Percent Due 2018
Debt Instrument [Line Items]
Long-term debt		$ 125						$ 125
Repayments of debt								$ 133
Debt instrument, interest rate, stated percentage		6.65%				6.65%		6.65%
Term Loan Credit Agreements 2016
Debt Instrument [Line Items]
Repayments of debt								$ 250
Notes 7.4 Percent Due 2019
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						7.40%
Notes 2.70 Percent Due 2022
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						2.70%