Debt - Debt Summary (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.60%	1.90%
Weighted Average Term	10 years 9 months 18 days	10 years 2 months 12 days
Debt	$ 17,135,668	$ 16,849,076
Credit Facilities [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	0.80%	0.80%
Weighted Average Term	2 years 6 months	2 years
Debt	$ 100,000	$ 171,794
Senior Notes [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	1.60%	2.00%
Weighted Average Term	11 years 8 months 12 days	11 years 2 months 12 days
Debt	$ 14,887,589	$ 14,275,870
Term Loans and Unsecured Other [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	0.80%	0.90%
Weighted Average Term	5 years 8 months 12 days	5 years 7 months 6 days
Debt	$ 1,405,981	$ 1,764,311
Secured Mortgage [Member]
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.40%	3.10%
Weighted Average Term	3 years 2 months 12 days	3 years
Debt	$ 742,098	$ 637,101