Debt - Narrative (Details) - USD ($)	6 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Renewed borrowing capacity	$ 14,500,000,000
Secured Debt [Member]
Debt Instrument [Line Items]
Weighted average interest rate	2.42%
Debt issuance costs	$ 84,000,000	$ 75,000,000
Secured Debt [Member] \| Securitization Notes Payable with Maturity Dates from 2021 to 2027 [Member]
Debt Instrument [Line Items]
Weighted average interest rate	1.71%
Debt instrument, face amount	$ 9,000,000,000.0
Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Weighted average interest rate	3.38%
Debt instrument, face amount	$ 46,100,000,000
Unsecured Senior Notes [Member] \| Senior Notes with Maturity Dates from 2024 to 2028 [Member]
Debt Instrument [Line Items]
Weighted average interest rate	3.41%
Debt instrument, face amount	$ 5,900,000,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuance costs	$ 115,000,000	$ 109,000,000
Line of Credit [Member]
Debt Instrument [Line Items]
Weighted average interest rate	3.15%
Debt instrument term	4 years
Maximum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Expiration period	6 years

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ 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
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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- Details

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