Summary of significant accounting policies (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($)	Jan. 01, 2020 USD ($)
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Maximum expected period of sale of property (in years)			1 year
Cost method investment ownership percentage	10.00%		10.00%
Percentage of total revenues	98.60%		98.70%
Contract with customer, asset, allowance for credit loss	$ 3,800		$ 3,800
Minimum percentage of taxable income to be distributed			90.00%
Percent of taxable income, generally distributed as dividend			100.00%
Income from rentals
Operating leases	538,880	$ 539,001	$ 1,515,396	$ 1,398,084
Revenues subject to the new lease accounting standard	539,892	539,620	1,517,869	1,399,931
Revenue	547,759	545,042	1,537,227	1,421,917
Direct financing lease, allowance for credit loss	2,800		2,800		$ 2,200
Credit loss related to trade receivables					$ 259
Cumulative Effect, Period of Adoption, Adjustment
Income from rentals
Receivables from revenue transactions within scope of revenue recognition	$ 16,100		$ 16,100
Land improvements | Maximum
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Estimated useful life			20 years
Buildings and building improvements | Maximum
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Estimated useful life			40 years
Canada
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Number of real estate properties | property	4		4
China
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Number of real estate properties | property	1		1
Income from rentals
Income from rentals
Revenue	$ 546,527	543,412	$ 1,533,593	1,416,873
Income from rentals | Cumulative Effect, Period of Adoption, Adjustment
Income from rentals
Revenues subject to the revenue recognition accounting standard	6,635	3,792	15,724	16,942
Income from rentals | Accounting Standards Update 2014-09 - Revenue from Contract with Customers
Income from rentals
Revenues subject to the revenue recognition accounting standard	6,635	3,792	15,724	16,942
Other income
Income from rentals
Revenue	$ 1,232	$ 1,630	$ 3,634	$ 5,044
Revenues subject to other accounting guidance
Property, plant and equipment depreciated on a straight-line basis using an estimated life
Percentage of total revenues	1.40%		1.30%
Income from rentals
Revenue	$ 7,900		$ 19,400