Land, Buildings and Improvements and Assets Held for Sale - Narratives (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($) property $ / €	Jun. 30, 2019 USD ($) property	Jun. 30, 2020 USD ($) property $ / €	Jun. 30, 2019 USD ($) property	Dec. 31, 2019 USD ($) property $ / €
Real Estate Properties
Decrease in value of balance sheet item due to foreign currency translation	$ (13,847)	$ 4,187	$ 38,353	$ 4,360
Direct financing lease, net investments reclassified	(752,630)		(752,630)		$ (896,549)
Investments in real estate
Total capitalized costs			265,829	289,766
Capitalized construction cost			$ 139,800
Number of construction projects | property			4		3
Unfunded commitment	109,200		$ 109,200		$ 227,800
Interest income from direct financing leases	$ 18,800	25,400	$ 38,900	52,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets		us-gaap:OtherAssets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent		us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
Assets held for sale, net	$ 0		$ 0		$ 104,010
Real Estate
Real Estate Properties
Number of Properties | property	1,216		1,216
Investments in real estate
Gross contract revenue	$ 1,427	$ 15,436	$ 7,394	$ 31,432
Properties disposed of by sale
Investments in real estate
Number of properties sold | property		4	4	5
Asset held for sale, not in discontinued operations
Real Estate Properties
Number of Properties | property					1
Investments in real estate
Assets held for sale, net					$ 104,000
Office Space in New York
Investments in real estate
Right of use asset	60,600		$ 60,600
Lease liability	60,700		60,700
In-place lease
Investments in real estate
Total capitalized costs			$ 36,000
Finite lived intangible assets useful life			18 years 8 months 12 days
Above-market rent
Investments in real estate
Total capitalized costs			$ 8,200
Finite lived intangible assets useful life			18 years 8 months 12 days
Net investments in direct financing lease
Investments in real estate
Number of properties sold | property			1
Land
Investments in real estate
Total capitalized costs			$ 33,100
Building
Investments in real estate
Total capitalized costs			193,300
Net Lease Intangible
Investments in real estate
Total capitalized costs			44,200
Construction in progress
Investments in real estate
Total capitalized costs			140,040
Construction in progress | Facility in Azambuja, Portugal
Investments in real estate
Funding commitment	26,800		26,800
Land, buildings and improvements
Investments in real estate
Assets held for sale, net	0		$ 0		$ 105,573
Land, buildings and improvements | Properties disposed of by sale
Investments in real estate
Number of properties sold | property			3
Decrease in carrying value of real estate			$ 2,100
Operating Lease
Real Estate Properties
Decrease in value of balance sheet item due to foreign currency translation			45,500
Depreciation	62,100	$ 56,500	128,000	$ 111,700
Investments in real estate
Total capitalized costs			270,623
Acquisition related costs			8,600
Operating Properties
Real Estate Properties
Depreciation	$ 700	$ 2,500	$ 1,400	$ 5,300
Hotel | Real Estate
Real Estate Properties
Number of Properties | property	1		1		2
Self-storage | Operating Properties
Real Estate Properties
Number of Properties | property	10		10		0
Hotel | Operating Properties
Real Estate Properties
Number of Properties | property	1		1		0
Reclassification
Real Estate Properties
Direct financing lease, net investments reclassified	$ 118,500		$ 118,500
Reclassification | Net investments in direct financing lease
Real Estate Properties
Number of Properties | property	53		53
EUR
Real Estate Properties
Decrease in exchange rate			0.30%
Foreign currency exchange rate | $ / €	1.1198		1.1198		1.1234