Investments in real estate - Acquired leases (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Acquired below-market leases
Real Estate Properties [Line Items]
Amortization of intangible assets	$ 57,700	$ 57,800	$ 30,300
Weighted average amortization period	5 years 4 months 24 days
Values of acquired leases
Value of intangible assets, gross	$ 579,267	477,377
Accumulated amortization	(237,682)	(189,302)
Value of intangible assets, net	341,585	288,075
Estimated annual amortization
2022	55,813
2023	47,836
2024	37,663
2025	31,532
2026	27,761
Thereafter	140,980
Acquired-in-Place Leases
Real Estate Properties [Line Items]
Amortization of intangible assets	$ 146,600	105,400	$ 49,100
Weighted average amortization period	8 years 3 months 18 days
Values of acquired leases
Value of intangible assets, gross	$ 987,213	712,380
Accumulated amortization	(377,341)	(250,056)
Value of intangible assets, net	609,872	$ 462,324
Estimated annual amortization
2022	137,100
2023	97,299
2024	70,442
2025	56,701
2026	46,568
Thereafter	$ 201,762

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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