Equity, Income Tax Effects on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Before-Tax Amount
Other comprehensive income (loss) before income tax expense (benefit)	$ 107	$ (468)	$ 449
Tax Expense (Benefit)
Income tax expense (benefit) related to items of other comprehensive income (loss)	(48)	10	(21)
Net Amount
Other comprehensive income (loss)	155	(478)	470
Foreign Currency Translation Adjustment [Member]
Before-Tax Amount
Other comprehensive income (loss), before reclassifications, before tax	349	(517)	514
Tax Expense (Benefit)
Other comprehensive income (loss), before reclassifications, tax expense (benefit)	0	0	0
Net Amount
Other comprehensive income (loss), before reclassifications, net of tax	349	(517)	514
Net Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Before-Tax Amount
Other comprehensive income (loss) before income tax expense (benefit)	(234)	49	(65)
Tax Expense (Benefit)
Income tax expense (benefit) related to items of other comprehensive income (loss)	(47)	10	(21)
Net Amount
Other comprehensive income (loss)	(187)	39	(44)
Net Actuarial Gain (Loss) [Member]
Before-Tax Amount
Other comprehensive income (loss), before reclassifications, before tax	(245)	1	(79)
Reclassification from accumulated other comprehensive loss, current period, before tax	38	63	50
Tax Expense (Benefit)
Other comprehensive income (loss), before reclassifications, tax expense (benefit)	(54)	0	(29)
Reclassification from accumulated other comprehensive loss, current period, tax expense (benefit)	9	14	18
Net Amount
Other comprehensive income (loss), before reclassifications, net of tax	(191)	1	(50)
Reclassification from accumulated other comprehensive loss, current period, net of tax	29	49	32
Prior Service Cost (Credit) [Member]
Before-Tax Amount
Other comprehensive income (loss), before reclassifications, before tax	(3)	7	(4)
Reclassification from accumulated other comprehensive loss, current period, before tax	(28)	(29)	(36)
Tax Expense (Benefit)
Other comprehensive income (loss), before reclassifications, tax expense (benefit)	(1)	1	(1)
Reclassification from accumulated other comprehensive loss, current period, tax expense (benefit)	(6)	(7)	(13)
Net Amount
Other comprehensive income (loss), before reclassifications, net of tax	(2)	6	(3)
Reclassification from accumulated other comprehensive loss, current period, net of tax	(22)	(22)	(23)
Miscellaneous Loss [Member]
Before-Tax Amount
Other comprehensive income (loss), before reclassifications, before tax	0		0
Tax Expense (Benefit)
Other comprehensive income (loss), before reclassifications, tax expense (benefit)	4		3
Net Amount
Other comprehensive income (loss), before reclassifications, net of tax	(4)		(3)
Curtailment and Settlement Loss [Member]
Before-Tax Amount
Reclassification from accumulated other comprehensive loss, current period, before tax	4	7	4
Tax Expense (Benefit)
Reclassification from accumulated other comprehensive loss, current period, tax expense (benefit)	1	2	1
Net Amount
Reclassification from accumulated other comprehensive loss, current period, net of tax	3	$ 5	$ 3
Net Gain (Loss) from Derivative Instruments Designated and Qualifying as Cash Flow Hedges [Member]
Before-Tax Amount
Other comprehensive income (loss), before reclassifications, before tax	(6)
Reclassification from accumulated other comprehensive loss, current period, before tax	(2)
Other comprehensive income (loss) before income tax expense (benefit)	(8)
Tax Expense (Benefit)
Other comprehensive income (loss), before reclassifications, tax expense (benefit)	(1)
Reclassification from accumulated other comprehensive loss, current period, tax expense (benefit)	0
Income tax expense (benefit) related to items of other comprehensive income (loss)	(1)
Net Amount
Other comprehensive income (loss), before reclassifications, net of tax	(5)
Reclassification from accumulated other comprehensive loss, current period, net of tax	(2)
Other comprehensive income (loss)	$ (7)