Retirement Programs - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Pension contributions	$ 32	$ 76
Minimum
Defined Benefit Plan Disclosure [Line Items]
Required contributions to pension plans for 2021	40
Maximum
Defined Benefit Plan Disclosure [Line Items]
Required contributions to pension plans for 2021	$ 50

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- Definition

Amount of contribution expected to be received by defined benefit plan from employer in remainder of current fiscal year. Excludes contribution previously paid by employer in current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921

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- Definition

Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
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-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585

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