Indebtedness - Principal Payments Due on Long-Term Borrowings (Detail) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 25, 2020	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (After March 31,)		$ 487,000,000	$ 487,000,000
2021		800,000,000	800,000,000
2022		500,000,000	500,000,000
2023		500,000,000	500,000,000
2024		500,000,000	500,000,000
Thereafter		3,972,000,000	3,972,000,000
Total principal payment		6,759,000,000	6,759,000,000	$ 5,603,000,000
4.50% 2012 Senior Notes, due 2022
Debt Instrument [Line Items]
2022		500,000,000	500,000,000
Total principal payment		500,000,000	500,000,000	500,000,000
4.875% 2013 Senior Notes, due 2024
Debt Instrument [Line Items]
2024		500,000,000	500,000,000
Total principal payment		500,000,000	500,000,000	500,000,000
5.25% 2014 Senior Notes (30-Year), due 2044
Debt Instrument [Line Items]
Thereafter		600,000,000	600,000,000
Total principal payment		600,000,000	$ 600,000,000	$ 600,000,000
Debt instrument, term			30 years	30 years
1.75% 2015 Senior Notes, due 2027
Debt Instrument [Line Items]
Thereafter		549,000,000	$ 549,000,000
Total principal payment		549,000,000	549,000,000	$ 561,000,000
2.75% 2017 Senior Notes, due 2021
Debt Instrument [Line Items]
2021		500,000,000	500,000,000
Total principal payment		500,000,000	500,000,000	500,000,000
2.625% 2017 Senior Notes, due 2023
Debt Instrument [Line Items]
2023		500,000,000	500,000,000
Total principal payment		500,000,000	500,000,000	500,000,000
3.25% 2017 Senior Notes, due 2028
Debt Instrument [Line Items]
Thereafter		500,000,000	500,000,000
Total principal payment		500,000,000	500,000,000	500,000,000
3.25% 2018 Senior Notes, due 2021
Debt Instrument [Line Items]
2021		300,000,000	300,000,000
Total principal payment		300,000,000	300,000,000	300,000,000
4.25% 2018 Senior Notes, due 2029
Debt Instrument [Line Items]
Thereafter		400,000,000	400,000,000
Total principal payment		400,000,000	400,000,000	400,000,000
4.875% 2018 Senior Notes, due 2048
Debt Instrument [Line Items]
Thereafter		400,000,000	400,000,000
Total principal payment		400,000,000	400,000,000	400,000,000
0.950% Senior Notes Due 2030
Debt Instrument [Line Items]
Thereafter		823,000,000	823,000,000
Total principal payment		823,000,000	823,000,000	$ 842,000,000
3.75% 2020 Senior Note, due 2025
Debt Instrument [Line Items]
Thereafter		700,000,000	700,000,000
Total principal payment	$ 700,000,000	$ 700,000,000	700,000,000
Debt instrument, term	5 years	5 years
Commercial Paper
Debt Instrument [Line Items]
2020 (After March 31,)		$ 487,000,000	487,000,000
Total principal payment		$ 487,000,000	$ 487,000,000