Leases - Cash Flow From Lease Transactions (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities
Operating cash outflows from finance leases	$ 8
Financing cash outflows from finance leases	22
Operating cash outflows from operating leases	1,541
ROU assets obtained in exchange for new finance lease liabilities	209
ROU assets obtained in exchange for new operating lease liabilities	6,481
ROU assets obtained in exchange for new finance lease liabilities - post adoption
ROU assets obtained in exchange for new operating lease liabilities - post adoption	$ 1,679

No definition available.

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- Definition

Gross amount of lessee's right to use underlying asset under finance lease.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Gross amount of lessee's right to use underlying asset under operating lease.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Amount of interest paid on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cash outflow for principal payment on finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

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-Publisher FASB
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-Section 50
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-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977

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+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in right-of-use asset obtained in exchange for finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

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-Publisher FASB
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+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

+ Details

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