Income Taxes, Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount
Income tax expense at statutory rates, amount		$ 828	$ 957	$ 862
U.S. state and Canadian provincial tax expense, net of federal income tax effect		124	83	36
Permanent differences:
Manufacturing deduction			(42)	(22)
Other		(9)	(9)	(13)
GILTI tax		67
Foreign tax credits		(50)
Effects of Tax Reform/Change in tax law	$ (1,900)	(12)	(1,862)	(7)
Tax effects of income associated with noncontrolling interests		(49)	(31)	(44)
Other, net		(20)	(45)	(47)
Income tax expense (benefit)		$ 879	$ (949)	$ 765
Effective Income Tax Rate Reconciliation, Percent
Income tax expense at statutory rates (percent)		19.60%	29.80%	27.10%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		2.90%	2.60%	1.10%
Permanent differences:
Manufacturing deduction (percent)			(1.30%)	(0.70%)
Other (percent)		(0.20%)	(0.30%)	(0.40%)
GILTI tax (percent)		1.60%
Foreign tax credits (percent)		(1.20%)
Effects of Tax Reform/Change in tax law (percent)		(0.30%)	(58.10%)	(0.20%)
Tax effects of income associated with noncontrolling interests (percent)		(1.20%)	(1.00%)	(1.40%)
Other, net (percent)		(0.50%)	(1.40%)	(1.50%)
Income tax expense (benefit) (percent)		20.70%	(29.70%)	24.00%
U.S. [Member]
Effective Income Tax Rate Reconciliation, Amount
Income tax expense at statutory rates, amount		$ 665	$ 799	$ 606
U.S. state and Canadian provincial tax expense, net of federal income tax effect		44	37	5
Permanent differences:
Manufacturing deduction			(42)	(22)
Other		(9)	(9)	(3)
GILTI tax		67
Foreign tax credits		(50)
Effects of Tax Reform/Change in tax law		(12)	(1,862)	0
Tax effects of income associated with noncontrolling interests		(49)	(31)	(44)
Other, net		(23)	(52)	(37)
Income tax expense (benefit)		$ 633	$ (1,160)	$ 505
Effective Income Tax Rate Reconciliation, Percent
Income tax expense at statutory rates (percent)		21.00%	35.00%	35.00%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		1.40%	1.60%	0.30%
Permanent differences:
Manufacturing deduction (percent)			(1.80%)	(1.30%)
Other (percent)		(0.30%)	(0.40%)	(0.20%)
GILTI tax (percent)		2.10%
Foreign tax credits (percent)		(1.60%)
Effects of Tax Reform/Change in tax law (percent)		(0.40%)	(81.60%)	0.00%
Tax effects of income associated with noncontrolling interests (percent)		(1.50%)	(1.40%)	(2.50%)
Other, net (percent)		(0.70%)	(2.30%)	(2.10%)
Income tax expense (benefit) (percent)		20.00%	(50.90%)	29.20%
International [Member]
Effective Income Tax Rate Reconciliation, Amount
Income tax expense at statutory rates, amount		$ 163	$ 158	$ 256
U.S. state and Canadian provincial tax expense, net of federal income tax effect		80	46	31
Permanent differences:
Manufacturing deduction			0	0
Other		0	0	(10)
GILTI tax		0
Foreign tax credits		0
Effects of Tax Reform/Change in tax law		0	0	(7)
Tax effects of income associated with noncontrolling interests		0	0	0
Other, net		3	7	(10)
Income tax expense (benefit)		$ 246	$ 211	$ 260
Effective Income Tax Rate Reconciliation, Percent
Income tax expense at statutory rates (percent)		15.30%	17.10%	17.70%
U.S. state and Canadian provincial tax expense, net of federal income tax effect (percent)		7.50%	5.00%	2.10%
Permanent differences:
Manufacturing deduction (percent)			(0.00%)	(0.00%)
Other (percent)		0.00%	0.00%	(0.70%)
GILTI tax (percent)		0.00%
Foreign tax credits (percent)		(0.00%)
Effects of Tax Reform/Change in tax law (percent)		0.00%	0.00%	(0.50%)
Tax effects of income associated with noncontrolling interests (percent)		(0.00%)	(0.00%)	(0.00%)
Other, net (percent)		0.30%	0.80%	(0.70%)
Income tax expense (benefit) (percent)		23.10%	22.90%	17.90%