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Real Estate, Operating Real Estate, Real Estate Under Construction, and Equity Investment in Real Estate - Narratives (Details) $ in Thousands					12 Months Ended
	Dec. 30, 2021 USD ($)	Oct. 29, 2021 USD ($)	Sep. 03, 2021 USD ($) property	Dec. 23, 2020 USD ($) property	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($)	Apr. 15, 2019	Apr. 14, 2019
Real Estate Properties
Number of properties (property) \| property					53
Effect of exchange rate fluctuation					$ (36,960)	$ 43,772	$ (4,509)
Net investments in direct financing leases					11,449	16,933
Net investments in real estate					1,942,545	2,124,244
Purchases of real estate					10,919	0	0
Proceeds from lease termination					4,900
Gain on lease termination					100
Placed into service					171,413	236,923
Capitalized interest					5,418	8,273	7,100
Interest income from direct financing lease					1,500	3,200	3,900
Operating lease cost					800	1,000	1,100
Reimbursable rent					400	400	400
Operating ROU assets — land leases					34,496	37,339
Operating lease payments					700	400	800
Amount awarded to other party						2,600
Proceeds from sale of real estate					162,164	6,101	50,846
Repayment of debt					171,205	26,679	132,160
Asset retirement obligation					1,200	3,300
Adjustments
Real Estate Properties
Net investments in direct financing leases					(1,800)
Net investments in real estate					1,800
Lease revenues- net-leased
Real Estate Properties
Allowance for accounts receivable written off						7,000
Noncash
Real Estate Properties
Accrued development cost					$ 5,000	$ 20,500
Net Lease Property
Real Estate Properties
Number of properties (property) \| property						3
Placed into service						$ 6,300
Zadar, Croatia \| Discontinued operations, disposed of by sale
Real Estate Properties
Proceeds from sale of real estate		$ 14,400
Zadar, Croatia \| Discontinued operations, disposed of by sale \| Land, Buildings and Improvements
Real Estate Properties
Number of properties sold \| property					1
Other real estate, period decrease					$ 11,900
Student Housing Operating Properties Located in Cardiff and Portsmouth, United Kingdom \| Discontinued operations, disposed of by sale
Real Estate Properties
Proceeds from sale of real estate			$ 147,800
Student Housing in Swansea, United Kingdom
Real Estate Properties
Operating ROU assets — land leases					$ 7,400	7,500
Lease term range (in years)					983 years
University in Accra, Ghana \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Real Estate Properties
Allowance for accounts receivable written off						2,800
Real Estate
Real Estate Properties
Effect of exchange rate fluctuation					$ (65,300)
Depreciation					37,200	30,500	29,500
Net investments in real estate					$ 1,313,590	1,268,035
Real Estate \| Student Housing Properties Located in Spain and Portugal
Real Estate Properties
Number of properties (property) \| property					4
Real Estate Under Operating Leases \| Industrial Facility Located in Houston, Texas
Real Estate Properties
Purchases of real estate	$ 10,900
Real Estate Under Operating Leases \| Industrial Facility Located in Houston, Texas \| Land
Real Estate Properties
Purchases of real estate	1,900
Real Estate Under Operating Leases \| Industrial Facility Located in Houston, Texas \| Building
Real Estate Properties
Purchases of real estate	7,100
Real Estate Under Operating Leases \| Industrial Facility Located in Houston, Texas \| Net Lease Intangible
Real Estate Properties
Purchases of real estate	$ 1,900
Amortization Period (Years)					15 years
Operating Real Estate
Real Estate Properties
Effect of exchange rate fluctuation					$ 1,500
Depreciation					16,200	16,000	15,200
Net investments in real estate					$ 397,553	$ 523,429
Operating Real Estate \| Self Storage
Real Estate Properties
Number of properties (property) \| property					65
Operating Real Estate \| Student Housing Operating Properties Located in Cardiff and Portsmouth, United Kingdom \| Discontinued operations, disposed of by sale \| Land, Buildings and Improvements
Real Estate Properties
Number of properties sold \| property			2
Other real estate, period decrease					$ 114,100
Build To Suit Projects
Real Estate Properties
Number of construction projects during period \| property					3	7
Unfunded commitment					$ 55,400	$ 174,900
Equity method investment \| Self Storage
Real Estate Properties
Number of properties (property) \| property					3
Equity method investment \| Self Storage \| Joint Venture
Real Estate Properties
Equity method investments, ownership percentage								100.00%	90.00%
Equity method investment \| Self-Storage Facilities Located In Canada \| Self Storage
Real Estate Properties
Number of properties (property) \| property				3
Proceeds from sale of real estate				$ 62,300
Recognized gain on sale						12,900
Income from investment, tax						$ 1,800
Repayment of debt				$ 31,800
Equity method investment \| Development Property In Vaughn Canada
Real Estate Properties
Recognized gain on sale							$ 200