Income Taxes, Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount
Income tax expense (benefit) at statutory rates		$ (445)	$ 671	$ 828
U.S. state and Canadian provincial tax expense (benefit), net of federal income tax effect		(6)	104	124
Permanent differences		(8)	(26)	(9)
CARES Act	[1]	(360)
GILTI tax	[2]		115	67
Lapse of federal statute of limitations		(39)
Foreign tax credits			(95)	(50)
Repatriation withholding tax			45
Change in tax law/Effects of Tax Reform		21		(12)	[2]
Tax effects of income associated with noncontrolling interests		(74)	(75)	(49)
Other, net		8	(37)	(20)
Income tax expense (benefit)		$ (903)	$ 702	$ 879
Effective Income Tax Rate Reconciliation, Percent
Income tax expense (benefit) at statutory rates (percent)		22.10%	19.20%	19.60%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		0.30%	3.00%	2.90%
Permanent differences (percent)		0.40%	(0.70%)	(0.20%)
CARES Act (percent)	[1]	17.90%
GILTI tax (percent)	[2]		3.30%	1.60%
Lapse of federal statute of limitations (percent)		1.90%
Foreign tax credits (percent)			(2.70%)	(1.20%)
Repatriation withholding tax (percent)			1.30%
Change in tax law/Effects of Tax Reform (percent)		(1.00%)		(0.30%)	[2]
Tax effects of income associated with noncontrolling interests (percent)		3.70%	(2.20%)	(1.20%)
Other, net (percent)		(0.40%)	(1.10%)	(0.50%)
Income tax expense (benefit) (percent)		44.90%	20.10%	20.70%
U.S. [Member]
Effective Income Tax Rate Reconciliation, Amount
Income tax expense (benefit) at statutory rates		$ (435)	$ 524	$ 665
U.S. state and Canadian provincial tax expense (benefit), net of federal income tax effect		(33)	16	44
Permanent differences		(23)	(36)	(9)
CARES Act	[1]	(360)
GILTI tax	[2]		115	67
Lapse of federal statute of limitations		(39)
Foreign tax credits			(95)	(50)
Repatriation withholding tax			45
Change in tax law/Effects of Tax Reform		0		(12)	[2]
Tax effects of income associated with noncontrolling interests		(66)	(77)	(49)
Other, net		7	(36)	(23)
Income tax expense (benefit)		$ (949)	$ 456	$ 633
Effective Income Tax Rate Reconciliation, Percent
Income tax expense (benefit) at statutory rates (percent)		21.00%	21.00%	21.00%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		1.60%	0.70%	1.40%
Permanent differences (percent)		1.10%	(1.50%)	(0.30%)
CARES Act (percent)	[1]	17.40%
GILTI tax (percent)	[2]		4.60%	2.10%
Lapse of federal statute of limitations (percent)		1.80%
Foreign tax credits (percent)			(3.80%)	(1.60%)
Repatriation withholding tax (percent)			1.80%
Change in tax law/Effects of Tax Reform (percent)		0.00%		(0.40%)	[2]
Tax effects of income associated with noncontrolling interests (percent)		3.20%	(3.10%)	(1.50%)
Other, net (percent)		(0.30%)	(1.40%)	(0.70%)
Income tax expense (benefit) (percent)		45.80%	18.30%	20.00%
International [Member]
Effective Income Tax Rate Reconciliation, Amount
Income tax expense (benefit) at statutory rates		$ (10)	$ 147	$ 163
U.S. state and Canadian provincial tax expense (benefit), net of federal income tax effect		27	88	80
Permanent differences		15	10	0
CARES Act	[1]	0
GILTI tax	[2]		0	0
Lapse of federal statute of limitations		0
Foreign tax credits			0	0
Repatriation withholding tax			0
Change in tax law/Effects of Tax Reform		21		0	[2]
Tax effects of income associated with noncontrolling interests		(8)	2	0
Other, net		1	(1)	3
Income tax expense (benefit)		$ 46	$ 246	$ 246
Effective Income Tax Rate Reconciliation, Percent
Income tax expense (benefit) at statutory rates (percent)		(16.10%)	14.80%	15.30%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		43.50%	8.90%	7.50%
Permanent differences (percent)		24.20%	1.00%	0.00%
CARES Act (percent)	[1]	0.00%
GILTI tax (percent)	[2]		0.00%	0.00%
Lapse of federal statute of limitations (percent)		0.00%
Foreign tax credits (percent)			0.00%	0.00%
Repatriation withholding tax (percent)			0.00%
Change in tax law/Effects of Tax Reform (percent)		33.90%		0.00%	[2]
Tax effects of income associated with noncontrolling interests (percent)		(12.90%)	0.20%	0.00%
Other, net (percent)		1.60%	(0.10%)	0.30%
Income tax expense (benefit) (percent)		74.20%	24.80%	23.10%

[1] See “CARES Act” on page 119 for a discussion of significant changes in tax law in the U.S that were enacted in 2020.

[2] Relates to the Tax Cuts and Jobs Act of 2017 (Tax Reform), which, among other provisions, resulted in a minimum tax on the income of international subsidiaries (the GILTI tax).