Debt - Summary of Debt (Non-Printing) (Detail)	Mar. 31, 2020	Dec. 31, 2019
4.70% senior notes due 2020
Debt Instrument [Line Items]
Interest rate	4.70%	4.70%
3.15% senior notes due 2021
Debt Instrument [Line Items]
Interest rate	3.15%	3.15%
3.75% senior notes due 2021
Debt Instrument [Line Items]
Interest rate	3.75%	3.75%
4.00% senior notes due 2022
Debt Instrument [Line Items]
Interest rate	4.00%
3.85% senior notes due 2023
Debt Instrument [Line Items]
Interest rate	3.85%	3.85%
4.00% senior notes due 2024
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%
3.90% senior notes due 2025
Debt Instrument [Line Items]
Interest rate	3.90%	3.90%
4.20% senior notes due 2026
Debt Instrument [Line Items]
Interest rate	4.20%	4.20%
5.375% senior notes due 2036
Debt Instrument [Line Items]
Interest rate	5.375%	5.375%
5.50% senior notes due 2046
Debt Instrument [Line Items]
Interest rate	5.50%	5.50%