Fair Value of Financial Instruments (Details) - Senior Notes - USD ($)	Sep. 30, 2019	Aug. 26, 2019
$500 2.350% senior notes due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face value of debt		$ 500,000,000.0
Interest rate on senior notes		2.35%
$700 2.950% senior notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face value of debt		$ 700,000,000.0
Interest rate on senior notes		2.95%
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed rate senior notes carrying amount	$ 5,300,000,000
Fair Value, Inputs, Level 2 \| $600 3.000% senior notes due 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	606,000,000
Face value of debt	$ 600,000,000
Interest rate on senior notes	3.00%
Fair Value, Inputs, Level 2 \| $500 2.800% senior notes due 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 507,000,000
Face value of debt	$ 500,000,000
Interest rate on senior notes	2.80%
Fair Value, Inputs, Level 2 \| $500 3.125% senior notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 512,000,000
Face value of debt	$ 500,000,000
Interest rate on senior notes	3.125%
Fair Value, Inputs, Level 2 \| $700 3.650% senior notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 736,000,000
Face value of debt	$ 700,000,000
Interest rate on senior notes	3.65%
Fair Value, Inputs, Level 2 \| $500 2.350% senior notes due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 500,000,000
Face value of debt	$ 500,000
Interest rate on senior notes	2.35%
Fair Value, Inputs, Level 2 \| $300 3.850% senior notes due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 322,000,000
Face value of debt	$ 300,000,000
Interest rate on senior notes	3.85%
Fair Value, Inputs, Level 2 \| $700 3.800% senior notes due 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 751,000,000
Face value of debt	$ 700,000,000
Interest rate on senior notes	3.80%
Fair Value, Inputs, Level 2 \| $800 4.200% senior notes due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 878,000,000
Face value of debt	$ 800,000,000
Interest rate on senior notes	4.20%
Fair Value, Inputs, Level 2 \| $700 2.950% senior notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 702,000,000
Face value of debt	$ 700,000,000
Interest rate on senior notes	2.95%

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=114775744&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
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
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