Investments in Real Estate - Acquisitions (Details) $ in Thousands, £ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) ft² property state	Sep. 30, 2021 GBP (£) ft² property state	Sep. 30, 2020 USD ($) ft² property state	Sep. 30, 2020 GBP (£) ft² property state
Real Estate [Line Items]
Number of properties	536	536	180	180
Leasable square feet (sq ft) | ft²	16,570,510	16,570,510	5,051,879	5,051,879
Investment | $	$ 3,775,874		$ 1,298,853
Weighted average lease term (years)	12 years 7 months 6 days	12 years 7 months 6 days	13 years 1 month 6 days	13 years 1 month 6 days
Initial average cash lease yield (percent)	5.50%	5.50%	6.30%	6.30%
U.K.
Real Estate [Line Items]
Investment | £				£ 356.7
New properties
Real Estate [Line Items]
Number of properties, new	486	486	167	167
Leasable square feet (sq ft) | ft²	14,443,555	14,443,555	4,215,292	4,215,292
Investment | $	$ 3,593,917		$ 1,275,552
Weighted average lease term (years)	12 years 4 months 24 days	12 years 4 months 24 days	13 years 1 month 6 days	13 years 1 month 6 days
Initial average cash lease yield (percent)	5.50%	5.50%	6.30%	6.30%
New properties | U.S.
Real Estate [Line Items]
Number of properties, new	415	415	154	154
Number of states | state	38	38	28	28
Leasable square feet (sq ft) | ft²	9,226,363	9,226,363	3,002,461	3,002,461
Investment | $	$ 2,073,101		$ 821,830
Weighted average lease term (years)	13 years 9 months 18 days	13 years 9 months 18 days	14 years 9 months 18 days	14 years 9 months 18 days
Initial average cash lease yield (percent)	5.50%	5.50%	6.20%	6.20%
New properties | Europe (UK and Spain)
Real Estate [Line Items]
Number of properties, new	71	71
Leasable square feet (sq ft) | ft²	5,217,192	5,217,192
Investment | $	$ 1,520,816
Weighted average lease term (years)	10 years 6 months	10 years 6 months
Initial average cash lease yield (percent)	5.50%	5.50%
New properties | U.K.
Real Estate [Line Items]
Number of properties, new			13	13
Leasable square feet (sq ft) | ft²			1,212,831	1,212,831
Investment | $			$ 453,722
Weighted average lease term (years)			10 years	10 years
Initial average cash lease yield (percent)			6.40%	6.40%
Properties under development
Real Estate [Line Items]
Number of properties, under development	50	50
Leasable square feet (sq ft) | ft²	2,126,955	2,126,955
Investment | $	$ 181,957
Weighted average lease term (years)	15 years 9 months 18 days	15 years 9 months 18 days
Initial average cash lease yield (percent)	5.90%	5.90%
Properties under development | U.S.
Real Estate [Line Items]
Number of properties, under development			13	13
Leasable square feet (sq ft) | ft²			836,587	836,587
Investment | $			$ 23,301
Weighted average lease term (years)			16 years 3 months 18 days	16 years 3 months 18 days
Initial average cash lease yield (percent)			6.40%	6.40%
Properties under development | U.K.
Real Estate [Line Items]
Number of properties, under development	1	1
Investment | £		£ 4.7