Fair Value Measurements (Narrative) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) reporting_unit	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of reporting units | reporting_unit		4
Goodwill, impairment loss		$ 579	$ 0	$ 0
Impairment of intangible assets (excluding goodwill)		168	0	$ 0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value		4,170	$ 4,950
EMEA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment loss	$ 579	579
Impairment of intangible assets (excluding goodwill)	$ 168	$ 168
Goodwill | Discounted Cash Flow Analysis | EMEA | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, measurement input	0.12
Minimum | Other Intangible Assets | Relief-From-Royalty Method | EMEA | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets (excluding goodwill), measurement input	0.115
Minimum | Other Intangible Assets | Relief-From-Royalty Method | EMEA | Measurement Input, Royalty Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets (excluding goodwill), measurement input	0.015
Maximum | Other Intangible Assets | Relief-From-Royalty Method | EMEA | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets (excluding goodwill), measurement input	0.16
Maximum | Other Intangible Assets | Relief-From-Royalty Method | EMEA | Measurement Input, Royalty Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets (excluding goodwill), measurement input	0.035