Long-Term Debt - Debt Issuance, Repurchases, Repayments and Exchanges (Details) - Senior Notes - July Tender and Purchase - Subsequent Event $ in Millions	1 Months Ended
	Jul. 31, 2021 USD ($)
Long-term Debt Rollforward [Roll Forward]
Tender and purchase	$ (3,026)
2.700% senior notes due 2022
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.027%
Tender and purchase	$ (278)
2.700% senior notes due 2023
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.027%
Tender and purchase	$ (484)
3.450% senior notes due 2024
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.0345%
Tender and purchase	$ (81)
2.900% senior notes due 2024
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.029%
Tender and purchase	$ (1,620)
3.500% senior notes due 2025
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.035%
Tender and purchase	$ (229)
3.400% senior notes due 2026
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.034%
Tender and purchase	$ (224)
3.200% senior notes due 2026
Long-term Debt Rollforward [Roll Forward]
Interest rate	0.032%
Tender and purchase	$ (110)