Investments in Real Estate - Acquisitions Allocation (Details) £ in Thousands, $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2021 EUR (€)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 GBP (£)
Real Estate Properties Acquired [Abstract]
Weighted average amortization period for acquired lease intangible assets	12 years 9 months 18 days	12 years 9 months 18 days	12 years 9 months 18 days	15 years 9 months 18 days	15 years 9 months 18 days
Weighted average amortization period for acquired lease intangible liabilities	15 years 10 months 24 days	15 years 10 months 24 days	15 years 10 months 24 days	16 years 8 months 12 days	16 years 8 months 12 days
Real Estate Investment | U.S.
Real Estate Properties Acquired [Abstract]
Land	$ 1,059,300			$ 338,400
Buildings and improvements	1,795,800			760,000
Lease intangible assets	579,800			206,600
Other assets	503,700			52,600
Lease intangible liabilities	(92,200)			(9,300)
Other liabilities	(130,600)			(900)
Net	3,715,800			1,347,400
Allocated to other assets, financing receivables with above-market terms	161,500			51,900
Allocated to other assets, finance lease right-of-use assets	76,700
Allocated to other assets, investments in sales-type leases	5,800
Allocated to other assets, right-of-use assets under ground leases accounted for as operating leases	259,700			$ 689
Allocated to other liabilities, deferred rent on below-market leases	27,100
Allocated to other liabilities, lease liabilities under ground leases accounted for as operating leases	67,400
Allocated to other liabilities, finance lease liabilities	$ 36,100
Real Estate Investment | U.K.
Real Estate Properties Acquired [Abstract]
Land | £		£ 422,300			£ 253,400
Buildings and improvements | £		904,300			259,100
Lease intangible assets | £		249,000			145,300
Other assets | £		40,400			50,600
Lease intangible liabilities | £		(6,800)			(600)
Other liabilities | £		(300)			0
Net | £		1,608,900			707,800
Allocated to land, right of use assets under long-term ground leases | £		5,500			£ 88,800
Allocated to other assets, financing receivables with above-market terms | £		7,200
Allocated to other assets, finance lease right-of-use assets | £		33,200
Allocated to other assets, right-of-use assets under ground leases accounted for as operating leases | £		13
Allocated to other liabilities, lease liabilities under ground leases accounted for as operating leases | £		13
Allocated to other liabilities, mortgage premium | £		£ 288
Real Estate Investment | Spain
Real Estate Properties Acquired [Abstract]
Land | €			€ 108.4
Buildings and improvements | €			168.8
Lease intangible assets | €			37.8
Other assets | €			21.9
Lease intangible liabilities | €			0.0
Other liabilities | €			(16.5)
Net | €			€ 320.4