Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Gross rental expense, post ASC adoption	$ 72	$ 53
Gross rental expense, pre-ASC adoption			$ 64
Sublease rental income, post ASC adoption	12	10
Sublease rental income, pre-ASC adoption			2
Operating lease, not yet commenced	0
Finance lease, not yet commenced	0
Operating lease, lease income	$ 312	$ 320	$ 522
Operating lease, lease income (as a percent)	4.00%	4.00%	6.00%

Lessee, Finance Lease, Lease Not Yet Commenced

No definition available.

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- Definition

Lessee, Operating Lease, Lease Not Yet Commenced

+ References

No definition available.

+ Details

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- Definition

Operating Lease, Lease Income, Percent of Operating Revenue

+ References

No definition available.

+ Details

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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977

+ Details

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Balance Type:	debit
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- Definition

Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919372-209981

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=121561866&loc=SL77919311-209978

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 6A
-URI http://asc.fasb.org/extlink&oid=121640914&loc=SL77927221-108306

+ Details

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- Definition

The total amount of sublease rental income recognized during the period that reduces the entity's rent expense incurred under operating leases.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=121580752&loc=d3e38371-112697

+ Details

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ 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 (e)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

+ Details

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Period Type:	duration