Long-term Debt - Summary of Long-term Debt (Parenthetical) (Detail)	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Apr. 24, 2019	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
3.65% Senior Notes due 2023
Debt Instrument [Line Items]
Debt instrument interest rate		3.65%			3.65%		3.65%
Debt instrument maturity date					2023		2023
3.90% Senior Notes due 2028
Debt Instrument [Line Items]
Debt instrument interest rate	3.90%	3.90%			3.90%		3.90%
Debt instrument maturity date	2028				2028		2028
1.375% Notes due 2026
Debt Instrument [Line Items]
Debt instrument interest rate		1.375%	1.375%		1.375%		1.375%
Debt instrument maturity date			2026		2026		2026
2.0% Notes due 2032
Debt Instrument [Line Items]
Debt instrument interest rate		2.00%	2.00%		2.00%		2.00%
Debt instrument maturity date			2032		2032		2032
0.25% Notes due 2027
Debt Instrument [Line Items]
Debt instrument interest rate		0.25%		0.25%	0.25%	0.25%	0.25%
Debt instrument maturity date				2027	2027	2027	2027
0.50% Notes due 2031
Debt Instrument [Line Items]
Debt instrument interest rate		0.50%		0.50%	0.50%	0.50%	0.50%
Debt instrument maturity date				2031	2031	2031	2031
2.65% Senior Notes due 2030
Debt Instrument [Line Items]
Debt instrument interest rate		2.65%	2.65%		2.65%		2.65%
Debt instrument maturity date			2030		2030		2030
2.40% Senior Notes due 2022
Debt Instrument [Line Items]
Debt instrument interest rate		2.40%			2.40%		2.40%
Debt instrument maturity date					2022		2022
4.00% Senior Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate		4.00%			4.00%		4.00%
Debt instrument maturity date					2025		2025
4.30% Senior Notes due 2029
Debt Instrument [Line Items]
Debt instrument interest rate		4.30%			4.30%		4.30%
Debt instrument maturity date					2029		2029
3.75% Senior Notes due 2024
Debt Instrument [Line Items]
Debt instrument interest rate		3.75%			3.75%		3.75%
Debt instrument maturity date					2024		2024
1.00% Guaranteed Notes due 2026
Debt Instrument [Line Items]
Debt instrument interest rate		1.00%			1.00%		1.00%
Debt instrument maturity date					2026		2026
2.65% Senior Notes due 2022
Debt Instrument [Line Items]
Debt instrument interest rate		2.65%			2.65%		2.65%
Debt instrument maturity date					2022		2022
0.00% Notes due 2024
Debt Instrument [Line Items]
Debt instrument interest rate		0.00%			0.00%	0.00%	0.00%
Debt instrument maturity date					2024	2024	2024
1.40% Senior Notes due 2025
Debt Instrument [Line Items]
Debt instrument interest rate		1.40%			1.40%		1.40%
Debt instrument maturity date		2025			2025		2025
3.63% Senior Notes due 2022
Debt Instrument [Line Items]
Debt instrument interest rate	3.63%	3.63%			3.63%		3.63%
Debt instrument maturity date	2022				2022		2022
7.00% Notes due 2038
Debt Instrument [Line Items]
Debt instrument interest rate		7.00%			7.00%		7.00%
Debt instrument maturity date					2038		2038
5.95% Notes due 2041
Debt Instrument [Line Items]
Debt instrument interest rate		5.95%			5.95%		5.95%
Debt instrument maturity date					2041		2041
5.13% Notes due 2043
Debt Instrument [Line Items]
Debt instrument interest rate		5.13%			5.13%		5.13%
Debt instrument maturity date					2043		2043
4.00% Notes due 2023
Debt Instrument [Line Items]
Debt instrument interest rate		4.00%			4.00%		4.00%
Debt instrument maturity date					2023		2023
3.70% Notes due 2024
Debt Instrument [Line Items]
Debt instrument interest rate		3.70%			3.70%		3.70%
Debt instrument maturity date					2024		2024
3.30% Senior Notes due 2021
Debt Instrument [Line Items]
Debt instrument interest rate		3.30%	3.30%		3.30%		3.30%
Debt instrument maturity date			2021		2021		2021
4.20% Senior Notes due 2021
Debt Instrument [Line Items]
Debt instrument interest rate		4.20%	4.20%		4.20%		4.20%
Debt instrument maturity date			2021		2021		2021