Senior Unsecured Notes and Secured Debt - Summary of Principal Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Amount
Debt issued	$ 1,208,241	$ 1,588,549
Debt issued	2,693	44,921
Ending balance	13,478,125
Senior unsecured notes
Amount
Beginning balance	11,509,533	10,427,562
Debt issued	1,250,000	1,600,000
Debt extinguished	(1,533,752)	(566,248)
Foreign currency	(17,437)	(48,037)
Ending balance	$ 11,208,344	$ 11,413,277
Weighted Avg. Interest Rate
Beginning balance	3.67%	4.03%
Debt issued	0.0250	0.0189
Debt extinguished	0.0242	0.0326
Foreign currency	0.0437	0.0414
Ending balance	3.71%	3.67%
Secured debt
Amount
Beginning balance	$ 2,378,073	$ 2,993,342
Debt issued	2,693	44,921
Debt extinguished	(70,144)	(491,506)
Principal payments	(48,710)	(46,585)
Foreign currency	7,869	(30,984)
Ending balance	$ 2,269,781	$ 2,469,188
Weighted Avg. Interest Rate
Beginning balance	3.27%	3.63%
Debt issued	0.0375	0.0258
Debt extinguished	0.0602	0.0261
Principal payments	0.0339	0.0360
Foreign currency	0.0297	0.0319
Ending balance	3.10%	3.16%