Debt (Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 11,706	$ 10,785
Debt, current portion	1,268	637
Debt, net of current portion	10,438	10,148
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	3,663	3,036
Loans Payable [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	3,167	2,976
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	2,835	2,400
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	879	1,264
Secured Debt [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	967	974
Finance Lease Obligations [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	73	105
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 122	$ 30

Amount of short-term and long-term debt and lease obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Section S99
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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Amount of long-term debt and lease obligation, classified as current.

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