Fair Value (Details) - Senior notes - USD ($)	Dec. 31, 2019	Aug. 26, 2019	Aug. 28, 2018	Dec. 19, 2016	Dec. 07, 2015	Nov. 21, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 5,300,000,000
$600 3.000% senior notes due 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 600,000,000				$ 600,000,000.0
Interest rate	3.00%				3.00%
$600 3.000% senior notes due 2020 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 605,000,000
$500 2.800% senior notes due 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 500,000,000			$ 500,000,000.0
Interest rate	2.80%			2.80%
$500 2.800% senior notes due 2021 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 507,000,000
$500 3.125% senior notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 500,000,000					$ 500,000,000.0
Interest rate	3.125%					3.125%
$500 3.125% senior notes due 2022 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 514,000,000
$700 3.650% senior notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 700,000,000		$ 700,000,000.0
Interest rate	3.65%		3.65%
$700 3.650% senior notes due 2023 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 735,000,000
$500 2.350% senior notes due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 500,000,000	$ 500,000,000.0
Interest rate	2.35%	2.35%
$500 2.350% senior notes due 2024 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 502,000,000
$300 3.850% senior notes due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 300,000,000				$ 300,000,000.0
Interest rate	3.85%				3.85%
$300 3.850% senior notes due 2025 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 324,000,000
$700 3.800% senior notes due 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 700,000,000			$ 700,000,000.0
Interest rate	3.80%			3.80%
$700 3.800% senior notes due 2026 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 754,000,000
$800 4.200% senior notes due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 800,000,000		$ 800,000,000.0
Interest rate	4.20%		4.20%
$800 4.200% senior notes due 2028 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 880,000,000
$700 2.950% senior notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Face amount of debt	$ 700,000,000	$ 700,000,000.0
Interest rate	2.95%	2.95%
$700 2.950% senior notes due 2029 | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 710,000,000