Tax Matters (Tax Contingencies) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2017	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Income Tax Contingency [Line Items]
Net liabilities associated with uncertain tax positions		$ 161	$ 180		$ 182		$ 161
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, January 1			(185)	[1]	(164)	[1]	(68)
Increases based on tax positions taken during a prior period		(15)
Decreases based on tax positions taken during a prior period	[2],[3]		12		6		12
Increases based on tax positions taken during the current period	[3],[4]		(8)		(11)		(107)
Lapse in statute of limitations			2		2		3
Balance, December 31	[1]	(164)	(182)		(185)		(164)
Net interest expense			2		1		1
Gross accrued interest		7	9		8		7
Gross accrued penalties		4	3		3		4
Other non-current assets
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, January 1			(3)		(3)
Balance, December 31		(3)	(3)		(3)		(3)
Noncurrent Deferred Tax Assets
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, January 1			(3)		(3)
Balance, December 31		(3)	(2)		(3)		(3)
Other Taxes Payable
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, January 1			(182)		(161)
Increases based on tax positions taken during a prior period	[3],[5]		(3)		(24)		(4)
Balance, December 31		$ (161)	(180)		(182)		(161)
Belgium
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Settlements	[6]		$ 0		$ 6		$ 0

[1] In 2019, included in Noncurrent deferred tax assets and Other noncurrent assets ($2 million) and Other taxes payable ($180 million). In 2018, included in Noncurrent deferred tax assets and Other noncurrent assets ($3 million) and Other taxes payable ($182 million). In 2017, included in Noncurrent deferred tax assets and Other noncurrent assets ($3 million) and Other taxes payable ($161 million).

[2] In 2019, the decreases are primarily related to movements on prior year positions and effective settlement of certain issues with non-U.S. tax authorities, including movements in foreign translation adjustments on prior year positions. In 2018, the decreases are primarily related to movements on prior year positions and closure of audits with U.S. and non-U.S. tax authorities, including movements in foreign translation adjustments on prior year positions. In 2017, the decreases are primarily related to movements on prior year positions and effective settlement of certain issues with U.S. and non-U.S. tax authorities. See A. Taxes on Income.

[3] Primarily included in Provision for taxes on income.

[4] In 2017, the increases are primarily related to the impact of the Tax Act. See A. Taxes on Income.

[5] In 2019, the increases are primarily related to movements on prior year positions. In 2018, the increases are primarily related to the impact of the Tax Act and movements on prior year positions. In 2017, the increases are primarily related to movements on prior year positions, including movements in foreign translation adjustments on prior year positions. See A. Taxes on Income.

[6] In 2018, the decreases are due to settlements with U.S. and non-U.S. tax authorities. See A. Taxes on Income.