Borrowings - Interest on Debt (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Interest on Debt
Interest capitalized	$ 2	$ 5
Total interest paid and accrued	388	449
Cost of financing
Interest on Debt
Interest paid	106	119
Interest expense
Interest on Debt
Interest paid	$ 280	$ 326

Amount of interest capitalized during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
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Total interest costs incurred during the period and either capitalized or charged against earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
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Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

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-Name Accounting Standards Codification
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