Real Estate - Schedule of Development in Process Activities (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($) property
Property, Plant and Equipment [Line Items]
Number of properties under development \| property	3	3	3
Real estate under development, beginning balance	$ 234,338	$ 247,349	$ 253,402
Transfers In	0	66,812
Capitalized Costs	1,766	8,062
Transfers Out	$ 14,777	$ 80,927
Core Portfolio
Property, Plant and Equipment [Line Items]
Number of properties under development \| property	0	0	0
Real estate under development, beginning balance	$ 50,251	$ 63,875	$ 60,863
Transfers In	0	0
Capitalized Costs	933	3,012
Transfers Out	$ 14,557	$ 0
Fund Portfolio \| Fund II
Property, Plant and Equipment [Line Items]
Number of properties under development \| property	0	0	0
Real estate under development, beginning balance	$ 75,192	$ 74,657	$ 10,703
Transfers In	0	66,812
Capitalized Costs	535	3,612
Transfers Out	$ 0	$ 6,470
Fund Portfolio \| Fund III
Property, Plant and Equipment [Line Items]
Number of properties under development \| property	1	1	1
Real estate under development, beginning balance	$ 23,416	$ 23,139	$ 36,240
Transfers In	0	0
Capitalized Costs	277	70
Transfers Out	$ 0	$ 13,171
Fund Portfolio \| Fund IV
Property, Plant and Equipment [Line Items]
Number of properties under development \| property	2	2	2
Real estate under development, beginning balance	$ 85,479	$ 85,678	$ 145,596
Transfers In	0	0
Capitalized Costs	21	1,368
Transfers Out	$ 220	$ 61,286