Financial Instruments (Narrative) (Details) $ in Billions			3 Months Ended
	Mar. 08, 2019 USD ($)	Mar. 08, 2019 CAD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 08, 2019 CAD ($)	Dec. 31, 2018 USD ($)
Derivative [Line Items]
Derivative, gain (loss) on derivative, net			$ (425,000,000)	$ 0
Equity Contract, Preemptive Rights [Member]
Derivative [Line Items]
Unrealized gain (loss) on derivatives			(132,000,000)
Equity Contract, Warrant [Member]
Derivative [Line Items]
Unrealized gain (loss) on derivatives			(262,000,000)
Net Investment Hedging [Member] | Foreign currency contracts [Member]
Derivative [Line Items]
Derivative, notional amount			1,226,000,000			$ 1,226,000,000
Cronos Group Inc. [Member]
Derivative [Line Items]
Equity method investments, purchase price	$ 1,800,000,000	$ 2.4
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative asset, notional amount	$ 1,800,000,000				$ 2.4
Derivative, gain (loss) on derivative, net			(31,000,000)
Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Debt instrument, fair value disclosure			4,851,000,000
Long-term debt			$ 4,740,000,000			$ 0