Debt - Debt Summary (Parenthetical) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.70%	1.90%
Debt	$ 16,503,458	$ 16,849,076
Percentage of outstanding debt	0.00%
GBP
Debt Instrument [Line Items]
Weighted Average Interest Rate	2.20%	2.20%
Debt	$ 1,027,910	$ 1,019,480
Percentage of outstanding debt	6.20%	6.10%
CAD
Debt Instrument [Line Items]
Weighted Average Interest Rate	2.70%	2.70%
Debt	$ 288,045	$ 285,708
Percentage of outstanding debt	1.70%	1.70%
EUR
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.10%	1.40%
Debt	$ 6,963,034	$ 6,549,676
Percentage of outstanding debt	42.20%	38.80%
JPY
Debt Instrument [Line Items]
Weighted Average Interest Rate	0.80%	0.80%
Debt	$ 2,460,056	$ 2,877,247
Percentage of outstanding debt	14.90%	17.10%
USD
Debt Instrument [Line Items]
Weighted Average Interest Rate	2.60%	2.80%
Debt	$ 5,764,413	$ 6,116,965
Percentage of outstanding debt	35.00%	36.30%