Borrowings (Long-term Debt Including Unamortized Debt Discounts and Premiums) (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Senior Notes	$ 8,581	$ 7,481
Unamortized discount — net	(13)	(14)
Debt issuance costs	(42)	(37)
Total long-term debt	$ 8,526	7,430
Senior Notes [Member] \| Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	4.45%
Senior Notes	$ 700	700
Senior Notes [Member] \| Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.25%
Senior Notes	$ 600	600
Senior Notes [Member] \| Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.225%
Senior Notes	$ 256	256
Senior Notes [Member] \| Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	2.65%
Senior Notes	$ 800	800
Senior Notes [Member] \| Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.55%
Senior Notes	$ 500	500
Senior Notes [Member] \| Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.00%
Senior Notes	$ 375	375
Senior Notes [Member] \| Senior Notes Due March 2025 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	4.20%
Senior Notes	$ 600	0
Senior Notes [Member] \| Senior Notes Due May 2025 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.85%
Senior Notes	$ 750	750
Senior Notes [Member] \| Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.45%
Senior Notes	$ 350	350
Senior Notes [Member] \| Senior Notes Due 2027 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.20%
Senior Notes	$ 650	650
Senior Notes [Member] \| Senior Notes Due 2028 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.20%
Senior Notes	$ 700	700
Senior Notes [Member] \| Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	4.00%
Senior Notes	$ 600	600
Senior Notes [Member] \| Senior Notes Due May 2029 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	3.25%
Senior Notes	$ 600	600
Senior Notes [Member] \| Senior Notes Due 2030 [Member]
Debt Instrument [Line Items]
Fixed Interest Rate	4.625%
Senior Notes	$ 500	0
Senior Notes [Member] \| Floating Rate Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 600	$ 600
Senior Notes [Member] \| Floating Rate Senior Notes Due 2021 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread rate	0.32%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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- 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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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

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

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Balance Type:	debit
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- 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)
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-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

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- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	instant