Financial Instruments, Hedging Activities and Fair Value Measurements (Additional Information) (Details) € in Billions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 EUR (€)	Dec. 31, 2018 EUR (€)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	Dec. 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional amount								$ 560,000,000
Fair Value of Debt Instrument Designated as a Hedge of Net Investment in Foreign Operations			$ 2,600,000,000		$ 0
Accumulated pretax unrealized translation gains (losses) in AOCI, related to both the euro-denominated borrowings and the cross currency swaps that have been designated as hedges of net investments			5,187,000,000	$ 5,010,000,000	4,732,000,000	$ 4,983,000,000	$ 5,467,000,000		$ 5,672,000,000
Capital Lease Obligations			11,000,000		12,000,000
Short-term Debt			10,000,000		4,000,000
Long-term Debt			5,478,000,000		5,000,000,000
Long-lived assets fair value amount			5,666,000,000		5,101,000,000
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional amount								525,000,000
Currency Swap [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional amount								$ 575,000,000
Cash Flow Hedging [Member] | Foreign currency contracts [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional amount			71,000,000		50,000,000
Net Investment Hedging [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Long-term Debt | €	€ 2.3	€ 2.3
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Accumulated pretax unrealized translation gains (losses) in AOCI, related to both the euro-denominated borrowings and the cross currency swaps that have been designated as hedges of net investments			$ 188,000,000		$ 161,000,000