Debt - Summary of Debt (Parenthetical) (Detail) $ in Thousands, £ in Millions		Dec. 31, 2019 USD ($)		Dec. 05, 2019	Jul. 26, 2019	Dec. 31, 2018 USD ($)		Dec. 31, 2018 GBP (£)		Sep. 07, 2017	Mar. 24, 2017	Aug. 19, 2015	Apr. 17, 2014
Debt Instrument [Line Items]
Debt		$ 7,089,520
4.000% Senior Unsecured Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		4.00%	[1]			4.00%	[1]	4.00%	[1]			4.00%
Debt	[1]	$ 560,650				$ 573,350
2.550% Senior Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		2.55%	[1]	2.55%
Debt	[1]	$ 530,280
5.500% Senior Unsecured Notes Due 2024 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		5.50%				5.50%		5.50%					5.50%
Debt		$ 300,000				$ 300,000
6.375% Senior Unsecured Notes due 2024 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		6.375%				6.375%		6.375%
Debt		$ 500,000				$ 500,000
3.325% Senior Unsecured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		3.325%	[1]			3.325%	[1]	3.325%	[1]		3.325%
Debt	[1]	$ 560,650				$ 573,350
5.250% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		5.25%				5.25%		5.25%
Debt		$ 500,000				$ 500,000
5.000% Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		5.00%				5.00%		5.00%		5.00%
Debt		$ 1,400,000				$ 1,400,000
3.692% Senior Unsecured Notes due 2028 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		3.692%	[1]	3.692%
Debt	[1]	$ 795,420
4.625% Senior Unsecured Notes Due 2029 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate		4.625%			4.625%
Debt		$ 900,000
GBP-denominated Borrowings [Member]
Debt Instrument [Line Items]
Debt | £								£ 22

[1] Non-U.S. dollar denominated debt that reflects the exchange rate at period end.