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