Debt - Summary of Debt (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total gross long-term debt	$ 3,650	$ 2,700
Unamortized discount and deferred financing costs	(46)	(25)
Total net carrying amount	$ 3,604	$ 2,675
Unsecured Debt \| Unsecured 2021 Notes
Debt Instrument [Line Items]
Interest rate		2.30%
Total gross long-term debt		$ 650
Unsecured Debt \| Unsecured 2021 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)		$ 653
Unsecured Debt \| Unsecured 2022 Notes
Debt Instrument [Line Items]
Interest rate		2.60%
Total gross long-term debt		$ 400
Unsecured Debt \| Unsecured 2022 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)		$ 405
Unsecured Debt \| Unsecured 2026 Notes
Debt Instrument [Line Items]
Interest rate	3.40%	3.40%
Total gross long-term debt	$ 850	$ 850
Unsecured Debt \| Unsecured 2026 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)	$ 968	$ 893
Unsecured Debt \| Unsecured 2027 Notes
Debt Instrument [Line Items]
Interest rate	3.40%	3.40%
Total gross long-term debt	$ 400	$ 400
Unsecured Debt \| Unsecured 2027 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)	$ 453	$ 417
Unsecured Debt \| Unsecured 2030 Notes
Debt Instrument [Line Items]
Interest rate	1.35%
Total gross long-term debt	$ 500
Unsecured Debt \| Unsecured 2030 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)	$ 488
Unsecured Debt \| Unsecured 2047 Notes
Debt Instrument [Line Items]
Interest rate	4.50%	4.50%
Total gross long-term debt	$ 400	$ 400
Unsecured Debt \| Unsecured 2047 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)	$ 508	$ 456
Unsecured Debt \| Unsecured 2050 Notes
Debt Instrument [Line Items]
Interest rate	2.50%
Total gross long-term debt	$ 1,500
Unsecured Debt \| Unsecured 2050 Notes \| Significant Other Observable Inputs (Level 2)
Debt Instrument [Line Items]
Fair Value (Level 2)	$ 1,386

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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- Definition

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

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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.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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